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Sample records for bismuth titanate powders

  1. Synthesis and characterization of bismuth alkaline titanate powders

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M., E-mail: atorresh@ipn.mx [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Dominguez-Crespo, M.A. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Hernandez-Perez, M.A. [ESIQIE, Metalurgia, Instituto Politecnico Nacional, Mexico, D. F (Mexico); Garcia-Zaleta, D.S. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Brachetti-Sibaja, S.B. [CICATA-Altamira, Instituto Politecnico Nacional, Km. 14.5 Carretera Tampico Puerto Industrial Altamira, Altamira, Tamps. 89600 (Mexico); Instituto Tecnologico de Ciudad Madero, Av. 1o. de Mayo esq. Sor Juana Ines de la Cruz s/n Col. Los Mangos C.P.89440 Cd. Madero Tamaulipas (Mexico)

    2011-06-15

    In this work, samples of bismuth alkaline titanate, (K{sub 0.5}Na{sub 0.5}){sub (2-x/2)}Bi{sub (x/6)}TiO{sub 3}, (x = 0.05-0.75) have been prepared by conventional ceramic technique and molten salts. Metal oxides or carbonates powders were used as starting raw materials. The crystalline phase of the synthesized powders was identified by the X-ray diffraction (XRD) and particle morphology was characterized by scanning electron microscopy (SEM). Solid state reaction method was unsuccessful to obtain pellets. From XRD results, a rhombohedral structure was detected and the parameter lattice were estimated to be a = 5.5478 A and {alpha} = 59.48{sup o}. These parameters were used to refine the structure by Rietveld analysis. SEM results showed several morphologies. Apparently, bismuth is promoting the grain growth whose sizes vary from 30 nm to 180 nm It is expected that these materials can be utilized in practical applications as substitutes for lead zirconatetitanate (PZT)-based ceramics.

  2. Synthesis and structural characterization of Ce-doped bismuth titanate

    International Nuclear Information System (INIS)

    Pavlovic, Nikolina; Srdic, Vladimir V.

    2009-01-01

    Ce-modified bismuth titanate nanopowders Bi 4-x Ce x Ti 3 O 12 (x ≤ 1) have been synthesized using a coprecipitation method. DTA/TG, FTIR, XRD, SEM/EDS and BET methods were used in order to investigate the effect of Ce-substitution on the structure, morphology and sinterability of the obtained powders. The phase structure investigation revealed that after calcinations at 600 deg. C powder without Ce addition exhibited pure bismuth titanate phase; however, powders with Ce (x = 0.25, 0.5 and 0.75) had bismuth titanate pyrochlore phase as the second phase. The strongest effect of Ce addition on the structure was noted for the powder with the highest amount of Ce (x = 1) having a cubic pyrochlore structure. The presence of pure pyrochlore phase was explained by its stabilization due to the incorporation of cerium ions in titanate structure. Ce-modified bismuth titanate ceramic had a density over 95% of theoretical density and the fracture in transgranular manner most probably due to preferable distribution of Ce in boundary region

  3. Fabrication of crystal-oriented barium-bismuth titanate ceramics in high magnetic field and subsequent reaction sintering

    International Nuclear Information System (INIS)

    Tanaka, Satoshi; Tomita, Yusuke; Furushima, Ryoichi; Uematsu, Keizo; Shimizu, Hiroyuki; Doshida, Yutaka

    2009-01-01

    High magnetic field was applied to fabricate novel lead-free piezoelectric ceramics with a textured structure. A compact of crystallographically oriented grains was prepared by dry forming in a high magnetic field from a mixed slurry of bismuth titanate and barium titanate powders. Bismuth titanate particles with a size of about 1 μ m were used as the host material. In the forming process, the slurry was poured into a mold and set in a magnetic field of 10 T until completely dried. Bismuth titanate particles were highly oriented in the slurry under the magnetic field. The dried powder compact consisted of highly oriented bismuth titanate particles and randomly oriented barium titanate particles. Barium bismuth titanate ceramics with a- and b-axis orientations were successfully produced from the dried compact by sintering at temperatures above 1100 deg. C.

  4. Bismuth titanate nanorods and their visible light photocatalytic properties

    International Nuclear Information System (INIS)

    Pei, L.Z.; Liu, H.D.; Lin, N.; Yu, H.Y.

    2015-01-01

    Highlights: • Bismuth titanate nanorods have been synthesized by a simple hydrothermal process. • The size of bismuth titanate nanorods can be controlled by growth conditions. • Bismuth titanate nanorods show good photocatalytic activities of methylene blue and Rhodamine B. - Abstract: Bismuth titanate nanorods have been prepared using a facile hydrothermal process without additives. The bismuth titanate products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and UV-vis diffusion reflectance spectrum. XRD pattern shows that the bismuth titanate nanorods are composed of cubic Bi 2 Ti 2 O 7 phase. Electron microscopy images show that the length and diameter of the bismuth titanate nanorods are 50-200 nm and 2 μm, respectively. Hydrothermal temperature and reaction time play important roles on the formation and size of the bismuth titanate nanorods. UV-vis diffusion reflectance spectrum indicates that bismuth titanate nanorods have a band gap of 2.58 eV. The bismuth titanate nanorods exhibit good photocatalytic activities in the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RB) under visible light irradiation. The bismuth titanate nanorods with cubic Bi 2 Ti 2 O 7 phase are a promising candidate as a visible light photocatalyst

  5. Study of barium bismuth titanate prepared by mechanochemical synthesis

    Directory of Open Access Journals (Sweden)

    Lazarević Z.Ž.

    2009-01-01

    Full Text Available Barium-bismuth titanate, BaBi4Ti4O15 (BBT, a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 °C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

  6. AB initio energetics of lanthanum substitution in ferroelectric bismuth titanate

    International Nuclear Information System (INIS)

    Shah, S.H.

    2012-01-01

    Density functional theory based electronic structure calculations play a vital role in understanding, controlling and optimizing physical properties of materials at microscopic level. In present study system of interest is bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/)/(BIT) which has wide range of applications such as a high temperature piezoelectric and one of the best material for memory devices. However, it also suffers from serious issues such as oxygen vacancies which degrade its performance as a memory element and piezoelectric material. In this context, the bulk and defect properties of orthorhombic bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/) and bismuth lanthanum titanate (Bi/sub 3.25/La/sub 0.75/Ti/sub 3/O/sub 12/)/(BLT, x=0.75) were investigated by using first principles calculations and atomistic thermodynamics. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies were computed. The study improves understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It was found that lanthanum incorporation could occur on either of the two distinct bismuth sites in the structure and that the effect of substitution is to increase the formation energy of nearby native oxygen vacancies. The results provide direct atomistic evidence over a range of chemical conditions for the suggestion that lanthanum incorporation reduces the oxygen vacancy concentration. Oxygen vacancies contribute to ferroelectric fatigue by interacting strongly with domain walls and therefore a decrease in their concentration is beneficial. (orig./A.B.)

  7. Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators.

    Science.gov (United States)

    Reichmann, Klaus; Feteira, Antonio; Li, Ming

    2015-12-04

    The ban of lead in many electronic products and the expectation that, sooner or later, this ban will include the currently exempt piezoelectric ceramics based on Lead-Zirconate-Titanate has motivated many research groups to look for lead-free substitutes. After a short overview on different classes of lead-free piezoelectric ceramics with large strain, this review will focus on Bismuth-Sodium-Titanate and its solid solutions. These compounds exhibit extraordinarily high strain, due to a field induced phase transition, which makes them attractive for actuator applications. The structural features of these materials and the origin of the field-induced strain will be revised. Technologies for texturing, which increases the useable strain, will be introduced. Finally, the features that are relevant for the application of these materials in a multilayer design will be summarized.

  8. Characterization and properties of barium bismuth titanate

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    Jelena D. Bobić

    2009-06-01

    Full Text Available BaBi4Ti4O15 (BBiT was prepared from stoichiometric amounts of BaTiO3 (BT and Bi4Ti3O12 (BIT obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. BBiTceramics were sintered at 1100°C, 1110°C and 1120°C for 1 h without pre-calcination step. The formation of phase and crystal structure of BT, BIT and BBiT were verified using X-ray analysis. The morphology of obtained powders and microstructure were examined using scanning electron microscopy. The electrical properties of sintered samples were carried out and BBiT shows behaviour typical for relaxor ferroelectrics and dielectric constant at room temperature is approximately 93.

  9. Yttrium bismuth titanate pyrochlore mixed oxides for photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Merka, Oliver

    2012-10-18

    In this work, the sol-gel synthesis of new non-stoichiometric pyrochlore titanates and their application in photocatalytic hydrogen production is reported. Visible light response is achieved by introducing bismuth on the A site or by doping the B site by transition metal cations featuring partially filled d orbitals. This work clearly focusses on atomic scale structural changes induced by the systematical introduction of non-stoichiometry in pyrochlore mixed oxides and the resulting influence on the activity in photocatalytic hydrogen production. The materials were characterized in detail regarding their optical properties and their atomic structure. The pyrochlore structure tolerates tremendous stoichiometry variations. The non-stoichiometry in A{sub 2}O{sub 3} rich compositions is compensated by distortions in the cationic sub-lattice for the smaller Y{sup 3+} cation and by evolution of a secondary phase for the larger Bi{sup 3+} cation on the A site. For TiO{sub 2} rich compositions, the non-stoichiometry leads to a special vacancy formation in the A and optionally O' sites. It is shown that pyrochlore mixed oxides in the yttrium bismuth titanate system represent very active and promising materials for photocatalytic hydrogen production, if precisely and carefully tuned. Whereas Y{sub 2}Ti{sub 2}O{sub 7} yields stable hydrogen production rates over time, the bismuth richer compounds of YBiTi{sub 2}O{sub 7} and Bi{sub 2}Ti{sub 2}O{sub 7} are found to be not stable under irradiation. This drawback is overcome by applying a special co-catalyst system consisting of a precious metal core and a Cr{sub 2}O{sub 3} shell on the photocatalysts.

  10. Texturing of sodium bismuth titanate-barium titanate ceramics by templated grain growth

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    Yilmaz, Huseyin

    2002-01-01

    Sodium bismuth titanate modified with barium titanate, (Na1/2Bi 1/2)TiO3-BaTiO3 (NBT-BT), is a candidate lead-free piezoelectric material which has been shown to have comparatively high piezoelectric response. In this work, textured (Na1/2Bi1/2)TiO 3-BaTiO3 (5.5mol% BaTiO3) ceramics with pc (where pc denotes the pseudocubic perovskite cell) orientation were fabricated by Templated Grain Growth (TGG) or Reactive Templated Grain Growth (RTGG) using anisotropically shaped template particles. In the case of TGG, molten salt synthesized SrTiO3 platelets were tape cast with a (Na1/2Bi1/2)TiO3-5.5mol%BaTiO3 powder and sintered at 1200°C for up to 12 hours. For the RTGG approach, Bi4Ti3O12 (BiT) platelets were tape cast with a Na2CO3, Bi2O3, TiO 2, and BaCO3 powder mixture and reactively sintered. The TGG approach using SrTiO3 templates gave stronger texture along [001] compared to the RTGG approach using BiT templates. The textured ceramics were characterized by X-ray and electron backscatter diffraction for the quality of texture. The texture function was quantified by the Lotgering factor, rocking curve, pole figures, inverse pole figures, and orientation imaging microscopy. Electrical and electromechanical property characterization of randomly oriented and pc textured (Na1/2Bi1/2)TiO 3-5.5 mol% BaTiO3 rhombohedral ceramics showed 0.26% strain at 70 kV/cm, d33 coefficients over 500 pC/N have been obtained for highly textured samples (f ˜ 90%). The piezoelectric coefficient from Berlincourt was d33 ˜ 200 pC/N. The materials show considerable hysteresis. The presence of hysteresis in the unipolar-electric field curve is probably linked to the ferroelastic phase transition seen in the (Na 1/2Bi1/2)TiO3 system on cooling from high temperature at ˜520°C. The macroscopic physical properties (remanent polarization, dielectric constant, and piezoelectric coefficient) of random and textured ([001] pc) rhombohedral perovskites were estimated by linear averaging of single

  11. Crystallinity and electrical properties of neodymium-substituted bismuth titanate thin films

    International Nuclear Information System (INIS)

    Chen, Y.-C.; Hsiung, C.-P.; Chen, C.-Y.; Gan, J.-Y.; Sun, Y.-M.; Lin, C.-P.

    2006-01-01

    We report on the properties of Nd-substituted bismuth titanate Bi 4-x Nd x Ti 3 O 12 (BNdT) thin films for ferroelectric non-volatile memory applications. The Nd-substituted bismuth titanate thin films fabricated by modified chemical solution deposition technique showed much improved properties compared to pure bismuth titanate. A pyrochlore free crystalline phase was obtained at a low annealing temperature of 640 deg. C and grain size was found to be considerably increased as the annealing temperature increased. The film properties were found to be strongly dependent on the Nd content and annealing temperatures. The measured dielectric constant of BNdT thin films was in the range 172-130 for Bi 4-x Nd x Ti 3 O 12 with x 0.0-0.75. Ferroelectric properties of Nd-substituted bismuth titanate thin films were significantly improved compared to pure bismuth titanate. For example, the observed 2P r and E c for Bi 3.25 Nd 0.75 Ti 3 O 12 , annealed at 680 deg. C, were 38 μC/cm 2 and 98 kV/cm, respectively. The improved microstructural and ferroelectric properties of BNdT thin films suggest their suitability for high density ferroelectric random access memory applications

  12. Combined experimental–theoretical study of the optoelectronic properties of non-stoichiometric pyrochlore bismuth titanate

    KAUST Repository

    Noureldine, Dalal

    2015-10-27

    A combination of experimental and computational methods was applied to investigate the crystal structure and optoelectronic properties of the non-stoichiometric pyrochlore Bi2−xTi2O7−1.5x. The detailed experimental protocol for both powder and thin-film material synthesis revealed that a non-stoichiometric Bi2−xTi2O7−1.5x structure with an x value of ∼0.25 is the primary product, consistent with the thermodynamic stability of the defect-containing structure computed using density functional theory (DFT). The approach of density functional perturbation theory (DFPT) was used along with the standard GGA PBE functional and the screened Coulomb hybrid HSE06 functional, including spin–orbit coupling, to investigate the electronic structure, the effective electron and hole masses, the dielectric constant, and the absorption coefficient. The calculated values for these properties are in excellent agreement with the measured values, corroborating the overall analysis. This study indicates potential applications of bismuth titanate as a wide-bandgap material, e.g., as a substitute for TiO2 in dye-sensitized solar cells and UV-light-driven photocatalysis.

  13. Barium strontium titanate powders prepared by spray pyrolysis

    International Nuclear Information System (INIS)

    Brankovic, G.; Brankovic, Z.; Goes, M.S.; Paiva-Santos, C.O.; Cilense, M.; Varela, J.A.; Longo, E.

    2005-01-01

    Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders were submicronic, consisting of spherical, polycrystalline particles, with internal nanocrystalline structure. Crystallite size of 10 nm, calculated using Rietveld refinement, is in a good agreement with results of HRTEM

  14. Cerium-modified Aurivillius-type sodium lanthanum bismuth titanate with enhanced piezoactivities

    International Nuclear Information System (INIS)

    Wang Chunming; Zhao Liang; Wang Jinfeng; Zheng Limei; Du Juan; Zhao Minglei; Wang Chunlei

    2009-01-01

    The electrical, piezoelectric and dielectric properties of cerium-modified Aurivillius-type sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) ceramics were investigated. It was found the piezoelectric activities of NLBT ceramics were significantly improved by cerium modification. The piezoelectric coefficient d 33 and Curie temperature T c for the 0.50 wt.% cerium-modified NLBT were found to be 29 pC/N and 573 deg. C, respectively. The reasons for piezoelectric activities improvement by cerium modification were given. A small dielectric abnormity was observed in NLBT ceramics, which can be suppressed by cerium modification.

  15. Practical ultrasonic transducers for high-temperature applications using bismuth titanate and Ceramabind 830

    Science.gov (United States)

    Xu, Janet L.; Batista, Caio F. G.; Tittmann, Bernhard R.

    2018-04-01

    Structural health monitoring of large valve bodies in high-temperature environments such as power plants faces several limitations: commercial transducers are not rated for such high temperatures, gel couplants will evaporate, and measurements cannot be made in-situ. To solve this, we have furthered the work of Ledford in applying a practical transducer in liquid form which hardens and air dries directly onto the substrate. The transducer material is a piezoceramic film composed of bismuth titanate and a high-temperature binding agent, Ceramabind 830. The effects of several fabrication conditions were studied to optimize transducer performance and ensure repeatability. These fabrication conditions include humidity, binder ratio, water ratio, substrate roughness, and film thickness. The final product is stable for both reactive and non-reactive substrates, has a quick fabrication time, and has an operating temperature up to the Curie temperature of BIT, 650°C, well beyond the safe operating temperature of PZT (150°C).

  16. Electrical characterization of strontium titanate borosilicate glass ceramics system with bismuth oxide addition using impedance spectroscopy

    International Nuclear Information System (INIS)

    Thakur, O.P.; Kumar, Devendra; Parkash, Om; Pandey, Lakshman

    2003-01-01

    The ac electrical data, measured in the frequency range 0.1 kHz-1 MHz, were used to study the electrical response of strontium titanate borosilicate glass ceramic system with bismuth oxide addition. Complex plane plots from these electrical data for various glass ceramic samples reveal contributions from simultaneously operating polarization mechanisms to overall dielectric behavior. The complex modulus (M * ) representation of electrical data for various glass ceramic samples were found to be more informative. Equivalent circuit models, which represent the electrical behavior of glass ceramic samples, were determined using complex non-linear least square (CNLS) fitting. An attempt has been made to understand the dielectric behavior of various glass ceramics in terms of contributions arising from different polarization processes occurring at glassy matrix, crystalline phases, glass to crystal interface region and blocking electrodes. Glass ceramics containing SrTiO 3 and TiO 2 (rutile) phases show thermally stable dielectric behavior

  17. Study of influence of fuel on dielectric and ferroelectric properties of bismuth titanate ceramics synthesized using solution based combustion technique

    International Nuclear Information System (INIS)

    Subohi, Oroosa; Malik, M M; Kurchania, Rajnish; Kumar, G S

    2015-01-01

    The effect of fuel characteristics on the processing and properties of bismuth titanate (BIT) ceramics obtained by solution combustion route using different fuels are reported in this paper. Dextrose, urea and glycine were used as fuel in this study. The obtained bismuth titanate ceramics were characterized by using XRD, SEM at different stages of sample preparation. It was observed that BIT obtained by using dextrose as fuel shows higher dielectric constant and higher remnant polarization due to smaller grain size and lesser c-axis growth as compared to the samples with urea and glycine as fuel. The electrical behavior of the samples with respect to temperature and frequency was also investigated to understand relaxation phenomenon. (paper)

  18. Bismuth Titanate Fabricated by Spray-on Deposition and Microwave Sintering For High-Temperature Ultrasonic Transducers.

    Science.gov (United States)

    Searfass, Clifford T; Pheil, C; Sinding, K; Tittmann, B R; Baba, A; Agrawal, D K

    2016-01-01

    Thick films of ferroelectric bismuth titanate (Bi4Ti3O12) have been fabricated by spray-on deposition in conjunction with microwave sintering for use as high-temperature ultrasonic transducers. The elastic modulus, density, permittivity, and conductivity of the films were characterized. Electro-mechanical properties of the films were estimated with a commercial d33 meter which gave 16 pC/N. This value is higher than typically reported for bulk bismuth titanate; however, these films withstand higher field strengths during poling which is correlated with higher d33 values. Films were capable of operating at 650 °C for roughly 5 min before depoling and can operate at 600 °C for at least 7 days.

  19. Effect of Two Different Superstrate Layers On Bismuth Titanate (BiT) Array Antennas

    Science.gov (United States)

    Wee, F. H.; Malek, F.; Al-Amani, A. U.; Ghani, Farid

    2014-01-01

    The microwave industry has shown increasing interest in electronic ceramic material (ECM) due to its advantages, such as light weight, low cost, low loss, and high dielectric strength. In this paper, simple antennas covered by superstrate layers for 2.30 GHz to 2.50 GHz are proposed. The antennas are compact and have the capability of producing high performance in terms of gain, directivity, and radiation efficiency. Bismuth titanate with high dielectric constant of 21, was utilized as the ECM, while the superstrate layers chosen included a split ring resonator and dielectric material. The superstrate layers were designed for some improvement in the performance of directivity, gain, and return loss. The proposed antennas were simulated and fabricated. The results obtained were small antennas that possess high gain and high directivity with 360°, omni-directional signal transmission that resonant types of conventional dipole antenna cannot achieve. The gain of the antenna with the superstrate layer was enhanced by about 1 dBi over the antenna without a superstrate layer at 2.40 GHz.

  20. High Gain and High Directive of Antenna Arrays Utilizing Dielectric Layer on Bismuth Titanate Ceramics

    Directory of Open Access Journals (Sweden)

    F. H. Wee

    2012-01-01

    Full Text Available A high gain and high directive microstrip patch array antenna formed from dielectric layer stacked on bismuth titanate (BiT ceramics have been investigated, fabricated, and measured. The antennas are designed and constructed with a combination of two-, four-, and six-BiT elements in an array form application on microwave substrate. For gain and directivity enhancement, a layer of dielectric was stacked on the BiT antenna array. We measured the gain and directivity of BiT array antennas with and without the dielectric layer and found that the gain of BiT array antenna with the dielectric layer was enhanced by about 1.4 dBi of directivity and 1.3 dB of gain over the one without the dielectric layer at 2.3 GHz. The impedance bandwidth of the BiT array antenna both with and without the dielectric layer is about 500 MHz and 350 MHz, respectively, which is suitable for the application of the WiMAX 2.3 GHz system. The utilization of BiT ceramics that covers about 90% of antenna led to high radiation efficiency, and small-size antennas were produced. In order to validate the proposed design, theoretical and measured results are provided and discussed.

  1. Molten salt synthesis of lead lanthanum zirconate titanate ceramic powders

    International Nuclear Information System (INIS)

    Cai Zongying; Xing Xianran; Li Lu; Xu Yeming

    2008-01-01

    Lead lanthanum zirconate titanate (Pb 0.95 La 0.03 )(Zr 0.52 Ti 0.48 )O 3 (PLZT) was synthesized by one step molten salt method with the starting materials of PbC 2 O 4 , La 2 O 3 , ZrO(NO 3 ) 2 .2H 2 O and TiO 2 in the NaCl-KCl eutectic mixtures in the temperature range of 700-1000 deg. C. The single phase of (Pb 0.95 La 0.03 )(Zr 0.52 Ti 0.48 )O 3 powders was prepared at a temperature as low as 850 deg. C for 5 h. The effects of process parameters, such as soaking temperature and time, salt species, and the amount of flux with respect to the starting materials were investigated. The growth process of the PLZT particles in the molten salt undergoes a transition from a diffusion controlled mechanism to an interfacial reaction controlled mechanism at 900 deg. C

  2. Piezoelectric properties and thermal stabilities of cobalt-modified potassium bismuth titanate

    International Nuclear Information System (INIS)

    Guo, Zhen-Lei; Wang, Chun-Ming; Zhao, Tian-Long; Yu, Si-Long; Cao, Zhao-Peng

    2013-01-01

    The cobalt-modified potassium bismuth titanate (K 0.5 Bi 4.5 Ti 4 O 15 , KBT) piezoelectric ceramics have been prepared using conventional solid–state reaction. X-ray diffraction analysis revealed that the cobalt-modified KBT ceramics have a pure four-layer (m = 4) Aurivillius-type structure. The dielectric, ferroelectric, and piezoelectric properties of cobalt-modified KBT ceramics were investigated in detail. The piezoelectric activities of KBT ceramics were significantly improved by the cobalt modification. The reasons for piezoelectric activities enhancement with cobalt modification were given. The piezoelectric coefficient d 33 and Curie temperature T c for the 5 mol% cobalt-modified KBT ceramics (KBT-Co5) were found to be 28 pC/N and 575 °C, respectively. The DC resistivity, frequency constants (N p and N t ), and electromechanical properties at elevated temperature were investigated, indicating the cobalt-modified KBT piezoelectric ceramics possess stable piezoelectric properties up to 500 °C. The results show the cobalt-modified KBT ceramics are potential materials for high temperature piezoelectric applications. - Highlights: • We examine the piezoelectric properties of the cobalt-modified K 0.5 Bi 4.5 Ti 4 O 15 . • A high level of piezoelectric activities (d 33 = 28 pC/N) are obtained. • High Curie temperature (T c = 575 °C) is acquired for the optimal composition. • The Co-modified K 0.5 Bi 4.5 Ti 4 O 15 is promising as high temperature materials

  3. Influence of calcination temperature on sol-gel synthesized single-phase bismuth titanate for high dielectric capacitor applications

    Energy Technology Data Exchange (ETDEWEB)

    Thiruramanathan, Pandirengan; Marikani, Arumugam [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Physics; Madhavan, Durairaj [Mepco Schlenk Engineering College, Tamil Nadu (India). Dept. of Chemistry; Bharadwaj, Suresh; Awasthi, Anand Mohan [UGC-DAE Consortium for Scientific Research, Indore (India). Thermodynamics Lab.

    2016-05-15

    An inexpensive sol-gel combustion method using citric acid as fuel has been used to synthesize bismuth titanate, Bi{sub 4}Ti{sub 3}O{sub 12} nanopowders. Thermogravimetric analysis proved that a calcination temperature of 900 C is sufficient for the preparation of single-phase bismuth titanate. X-ray diffraction and Fourier transform infrared spectroscopy are used to examine the influence of calcination temperature on the structural growth of the Bi{sub 4}Ti{sub 3}O{sub 12} nanopowder. The average crystallite size estimated by using the Scherrer method and the Williamson-Hall method was found to increase with calcination temperature. Photoluminescence behavior as a function of calcination temperature was observed at two different excitation wavelengths of 300 nm and 420 nm. The morphology of the particles analyzed using images obtained from field emission scanning electron microscopy displayed irregular, random sized, and spherical-shaped structures. The stoichiometry and purity of the nanopowder are confirmed by energy-dispersive spectroscopy. The broadband dielectric results established the highest dielectric constant (ε{sub r} = 450) for a frequency of 100 Hz achieved with a potential capacitance of 138 pF m{sup -2}. This establishes Bi{sub 4}Ti{sub 3}O{sub 12} as a promising dielectric material for achieving high energy density capacitors for the next-generation passive devices.

  4. Enhanced piezoelectric properties and excellent thermal stabilities of cobalt-modified Aurivillius-type calcium bismuth titanate (CaBi_4Ti_4O_1_5)

    International Nuclear Information System (INIS)

    Zhao, Tian-Long; Wang, Chun-Ming; Wang, Chun-Lei; Wang, Yi-Ming; Dong, Shuxiang

    2015-01-01

    Highlights: • Cobalt oxide modified CBT-based ceramics were prepared and investigated in detail. • XRPD analysis revealed Co ions enter into B-site of CBT-based ceramics. • CBT-Co4 ceramics show the enhanced d_3_3 of 14 pC/N and T_c of 782 °C. • CBT-Co4 ceramics present the improved high-temperature resistivity. • Thermal depoling behavior indicates CBT-Co4 ceramics exhibit good thermal stability. - Abstract: Bismuth layer-structured ferroelectric (BLSF) calcium bismuth titanate (CaBi_4Ti_4O_1_5, CBT) piezoelectric ceramics with 0.0–1.0 wt.% cobalt oxide (Co_2O_3) have been prepared via a conventional solid-state reaction method. Microstructural morphology and electrical properties of cobalt oxide-modified CBT ceramics were investigated in detail. X-ray powder diffraction (XRPD) analysis revealed that the cobalt oxide-modified CBT ceramics have a pure four-layer Aurivillius-type structure. The piezoelectric properties of CBT ceramics were significantly enhanced by cobalt oxide modifications. The piezoelectric coefficient d_3_3 and Curie temperature T_c of 0.2 wt.% cobalt oxide-modified CBT ceramics (CBT-Co4) are 14 pC/N and 782 °C, respectively. The DC resistivity and thermal depoling behavior at elevated temperature indicated that the CBT-Co4 ceramics exhibit good thermal stability, demonstrating that the CBT-Co4 ceramics are potential materials for high temperature piezoelectric applications.

  5. Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

    Energy Technology Data Exchange (ETDEWEB)

    Pakseresht, A.H., E-mail: amirh_pak@yahoo.com [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Rahimipour, M.R. [Department of Ceramics, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Vaezi, M.R. [Department of Nanotechnology and Advanced Materials, Materials and Energy Research Center, P.O. Box 31787-316, Karaj (Iran, Islamic Republic of); Salehi, M. [Department of Materials Engineering, Isfahan University of Technology, P.O. Box 84156-83111, Isfahan (Iran, Islamic Republic of)

    2016-04-15

    In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO{sub 3} powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

  6. Thermal plasma spheroidization and spray deposition of barium titanate powder and characterization of the plasma sprayable powder

    International Nuclear Information System (INIS)

    Pakseresht, A.H.; Rahimipour, M.R.; Vaezi, M.R.; Salehi, M.

    2016-01-01

    In this paper, atmospheric plasma spray method was used to produce dense plasma sprayable powder and thick barium titanate film. In this regard, the commercially feedstock powders were granulated and spheroidized by the organic binder and the thermal spray process, respectively. Scanning electron microscopy was used to investigate the microstructure of the produced powders and the final deposits. X-ray diffraction was also implemented to characterize phase of the sprayed powder. The results indicated that spheroidized powder had suitable flowability as well as high density. The micro-hardness of the film produced by the sprayed powders was higher than that of the film deposited by the irregular granules. Additionally, relative permittivity of the films was increased by decreasing the defects from 160 to 293 for film deposited using spheroidized powder. The reduction in the relative permittivity of deposits, in comparison with the bulk material, was due to the existence of common defects in the thermal spray process. - Highlights: • We prepare sprayable BaTiO_3 powder with no or less inside voids for plasma spray application for first time. • The sprayable powder has good flow characteristics and high density. • Powder spheroidization via plasma spray improves the hardness and dielectric properties of the deposited film.

  7. Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide

    Science.gov (United States)

    Ekström, Mattias; Khartsev, Sergiy; Östling, Mikael; Zetterling, Carl-Mikael

    2017-07-01

    4H-SiC electronics can operate at high temperature (HT), e.g., 300°C to 500°C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrating ferroelectric vanadium-doped bismuth titanate (BiTV) thin films on 4H-SiC for HT memory applications, with BiTV ferroelectric capacitors providing memory functionality. Film deposition was achieved by laser ablation on Pt (111)/TiO2/4H-SiC substrates, with magnetron-sputtered Pt used as bottom electrode and thermally evaporated Au as upper contacts. Film characterization by x-ray diffraction analysis revealed predominately (117) orientation. P- E hysteresis loops measured at room temperature showed maximum 2 P r of 48 μC/cm2, large enough for wide read margins. P- E loops were measurable up to 450°C, with losses limiting measurements above 450°C. The phase-transition temperature was determined to be about 660°C from the discontinuity in dielectric permittivity, close to what is achieved for ceramics. These BiTV ferroelectric capacitors demonstrate potential for use in HT NVM applications for SiC digital electronics.

  8. Titan

    Science.gov (United States)

    Müller-Wodarg, Ingo; Griffith, Caitlin A.; Lellouch, Emmanuel; Cravens, Thomas E.

    2014-03-01

    Introduction I. C. F. Müller-Wodarg, C. A. Griffith, E. Lellouch and T. E. Cravens; Prologue 1: the genesis of Cassini-Huygens W.-H. Ip, T. Owen and D. Gautier; Prologue 2: building a space flight instrument: a P.I.'s perspective M. Tomasko; 1. The origin and evolution of Titan G. Tobie, J. I. Lunine, J. Monteux, O. Mousis and F. Nimmo; 2. Titan's surface geology O. Aharonson, A. G. Hayes, P. O. Hayne, R. M. Lopes, A. Lucas and J. T. Perron; 3. Thermal structure of Titan's troposphere and middle atmosphere F. M. Flasar, R. K. Achterberg and P. J. Schinder; 4. The general circulation of Titan's lower and middle atmosphere S. Lebonnois, F. M. Flasar, T. Tokano and C. E. Newman; 5. The composition of Titan's atmosphere B. Bézard, R. V. Yelle and C. A. Nixon; 6. Storms, clouds, and weather C. A. Griffith, S. Rafkin, P. Rannou and C. P. McKay; 7. Chemistry of Titan's atmosphere V. Vuitton, O. Dutuit, M. A. Smith and N. Balucani; 8. Titan's haze R. West, P. Lavvas, C. Anderson and H. Imanaka; 9. Titan's upper atmosphere: thermal structure, dynamics, and energetics R. V. Yelle and I. C. F. Müller-Wodarg; 10. Titan's upper atmosphere/exosphere, escape processes, and rates D. F. Strobel and J. Cui; 11. Titan's ionosphere M. Galand, A. J. Coates, T. E. Cravens and J.-E. Wahlund; 12. Titan's magnetospheric and plasma environment J.-E. Wahlund, R. Modolo, C. Bertucci and A. J. Coates.

  9. Combined experimental–theoretical study of the optoelectronic properties of non-stoichiometric pyrochlore bismuth titanate

    KAUST Repository

    Noureldine, Dalal; Lardhi, Sheikha F.; Ziani, Ahmed; Harb, Moussab; Cavallo, Luigi; Takanabe, Kazuhiro

    2015-01-01

    A combination of experimental and computational methods was applied to investigate the crystal structure and optoelectronic properties of the non-stoichiometric pyrochlore Bi2−xTi2O7−1.5x. The detailed experimental protocol for both powder and thin

  10. Ferroelectric mesocrystals of bismuth sodium titanate: formation mechanism, nanostructure, and application to piezoelectric materials.

    Science.gov (United States)

    Hu, Dengwei; Kong, Xingang; Mori, Kotaro; Tanaka, Yasuhiro; Shinagawa, Kazunari; Feng, Qi

    2013-09-16

    Ferroelectric mesocrystals of Bi0.5Na0.5TiO3 (BNT) with [100]-crystal-axis orientation were successfully prepared using a topotactic structural transformation process from a layered titanate H1.07Ti1.73O4·nH2O (HTO). The formation reactions of BNT mesocrystals in HTO-Bi2O3-Na2CO3 and HTO-TiO2-Bi2O3-Na2CO3 reaction systems and their nanostructures were studied by XRD, FE-SEM, TEM, SAED, and EDS, and the reaction mechanisms were given. The BNT mesocrystals are formed by a topotactic structural transformation mechanism in the HTO-Bi2O3-Na2CO3 reaction system and by a combination mechanism of the topotactic structural transformation and epitaxial crystal growth in the HTO-TiO2-Bi2O3-Na2CO3 reaction system, respectively. The BNT mesocrystals prepared by these methods are constructed from [100]-oriented BNT nanocrystals. Furthermore, these reaction systems were successfully applied to the fabrication of [100]-oriented BNT ferroelectric ceramic materials. A BNT ceramic material with a high degree of orientation, high relative density, and small grain size was achieved.

  11. Size effect in barium titanate powders synthesized by different hydrothermal methods

    International Nuclear Information System (INIS)

    Sun Weian

    2006-01-01

    The size effect in barium titanate (BaTiO 3 ) was investigated both experimentally and theoretically. Tetragonal BaTiO 3 powders with average sizes from 80 to 420 nm were directly prepared by different hydrothermal methods. The tetragonality of the hydrothermal BaTiO 3 decreased with decreasing particle size, which exhibited a dependence on the synthesis method. A phenomenological model for the size effect was proposed to interpret the experimental observations. The influence of the defects, mainly the lattice hydroxyl, on the size effect was investigated to understand the correlation between the size effect and synthesis condition. The permittivities of BaTiO 3 powder at different particle sizes were calculated, which predicted a maximum permittivity of over 16 000 around the room-temperature critical size of ∼70 nm. The prediction was in good accordance with the experimental data reported recently

  12. Titan!

    Science.gov (United States)

    Matson, Dennis L.

    2010-05-01

    Cassini-Huygens achieved Saturnian orbit on July 1, 2004. The first order of business was the safe delivery of the Huygens atmospheric probe to Titan that took place on January 14, 2005. Huygens descended under parachute obtaining observations all the way down to a safe landing. It revealed Titan for the first time. Stunning are the similarities between Titan and the Earth. Viewing the lakes and seas, the fluvial terrain, the sand dunes and other features through the hazy, nitrogen atmosphere, brings to mind the geological processes that created analogous features on the Earth. On Titan frozen water plays the geological role of rock; liquid methane takes the role of terrestrial water. The atmospheres of both Earth and Titan are predominately nitrogen gas. Titan's atmosphere contains 1.5% methane and no oxygen. The surface pressure on Titan is 1.5 times the Earth's. There are aerosol layers and clouds that come and go. Now, as Saturn proceeds along its solar orbit, the seasons are changing. The effects upon the transport of methane are starting to be seen. A large lake in the South Polar Region seems to be filling more as winter onsets. Will the size and number of the lakes in the South grow during winter? Will the northern lakes and seas diminish or dry up as northern summer progresses? How will the atmospheric circulation change? Much work remains not only for Cassini but also for future missions. Titan has many different environments to explore. These require more capable instruments and in situ probes. This work was conducted at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration.

  13. Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Alexandre H. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Souza, Flavio L., E-mail: flavio.souza@ufabc.edu.br [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia 166, Bangu, Santo Andre, SP 09210-170 (Brazil); Chiquito, Adenilson J., E-mail: chiquito@df.ufscar.br [Departamento de Fisica, UFSCar-Federal University of Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Longo, Elson, E-mail: elson@iq.unesp.br [Instituto de Quimica de Araraquara, UNESP-Universidade Estadual Paulista, Rua Francisco Degni, CP 355 Araraquara, SP 14801-907 (Brazil); Leite, Edson R., E-mail: derl@power.ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Camargo, Emerson R., E-mail: camargo@ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil)

    2010-12-01

    Nanosized powders of lead lanthanum titanate (Pb{sub 1-x}La{sub x}TiO{sub 3}) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

  14. Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Pinto, Alexandre H.; Souza, Flavio L.; Chiquito, Adenilson J.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

    2010-01-01

    Nanosized powders of lead lanthanum titanate (Pb 1-x La x TiO 3 ) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

  15. Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos SP, 13565-905 (Brazil)], E-mail: camargo@ufscar.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos SP, 13565-905 (Brazil)], E-mail: derl@power.ufscar.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP, Sao Paulo State University Rua Francisco Degni, CP 355 Araraquara SP, 14801-907 Brazil (Brazil)], E-mail: elson@iq.unesp.br

    2009-02-05

    Lead zirconate titanate (PbZr{sub 1-x}Ti{sub x}O{sub 3}) was synthesized by the 'oxidant peroxo method (OPM)' with 'x' between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 deg. C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 deg. C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with 'x' up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 deg. C, and tetragonal structure when 'x' was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 deg. C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio.

  16. Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Camargo, Emerson R.; Leite, Edson R.; Longo, Elson

    2009-01-01

    Lead zirconate titanate (PbZr 1-x Ti x O 3 ) was synthesized by the 'oxidant peroxo method (OPM)' with 'x' between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 deg. C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 deg. C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with 'x' up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 deg. C, and tetragonal structure when 'x' was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 deg. C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio

  17. Enhanced piezoelectric properties and excellent thermal stabilities of cobalt-modified Aurivillius-type calcium bismuth titanate (CaBi{sub 4}Ti{sub 4}O{sub 15})

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Tian-Long [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Wang, Chun-Ming, E-mail: wangcm@sdu.edu.cn [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Wang, Chun-Lei; Wang, Yi-Ming [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Dong, Shuxiang [Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2015-11-15

    Highlights: • Cobalt oxide modified CBT-based ceramics were prepared and investigated in detail. • XRPD analysis revealed Co ions enter into B-site of CBT-based ceramics. • CBT-Co4 ceramics show the enhanced d{sub 33} of 14 pC/N and T{sub c} of 782 °C. • CBT-Co4 ceramics present the improved high-temperature resistivity. • Thermal depoling behavior indicates CBT-Co4 ceramics exhibit good thermal stability. - Abstract: Bismuth layer-structured ferroelectric (BLSF) calcium bismuth titanate (CaBi{sub 4}Ti{sub 4}O{sub 15}, CBT) piezoelectric ceramics with 0.0–1.0 wt.% cobalt oxide (Co{sub 2}O{sub 3}) have been prepared via a conventional solid-state reaction method. Microstructural morphology and electrical properties of cobalt oxide-modified CBT ceramics were investigated in detail. X-ray powder diffraction (XRPD) analysis revealed that the cobalt oxide-modified CBT ceramics have a pure four-layer Aurivillius-type structure. The piezoelectric properties of CBT ceramics were significantly enhanced by cobalt oxide modifications. The piezoelectric coefficient d{sub 33} and Curie temperature T{sub c} of 0.2 wt.% cobalt oxide-modified CBT ceramics (CBT-Co4) are 14 pC/N and 782 °C, respectively. The DC resistivity and thermal depoling behavior at elevated temperature indicated that the CBT-Co4 ceramics exhibit good thermal stability, demonstrating that the CBT-Co4 ceramics are potential materials for high temperature piezoelectric applications.

  18. Enhancement of the piezoelectric properties of sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15) through modification with cobalt

    International Nuclear Information System (INIS)

    Wang Chunming; Wang Jinfeng; Zheng Limei; Zhao Minglei; Wang Chunlei

    2010-01-01

    The dielectric, piezoelectric, and electromechanical properties of B-site cobalt-modified sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) piezoelectric ceramics were investigated. The piezoelectric properties of NLBT ceramics can be enhanced by cobalt modifications. The NLBT ceramics modified with 0.2 wt.% cobalt trioxide (NLBT-C4) possess good piezoelectric properties, with piezoelectric coefficient d 33 of 27 pC/N, electromechanical coupling factors (k p and k t ) of 6.5% and 28.5%, and mechanical quality factor Q m (k p mode) of 3400. The Curie temperature T c of cobalt-modified NLBT ceramics was found to slightly higher than that of pure NLBT ceramics. A large dielectric abnormity in dielectric loss tan δ was observed in NLBT ceramics, which can be significantly suppressed by cobalt modification. Thermal annealing studies presented the cobalt-modified NLBT ceramics possess stable piezoelectric properties.

  19. Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: camargo@ufscar.br; Barrado, Cristiano M. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil); Ribeiro, Caue [EMBRAPA Instrumentacao Agropecuaria, Rua XV de Novembro 1452, Sao Carlos SP 13560-970 (Brazil)], E-mail: caue@cnpdia.embrapa.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP-Sao Paulo State University, Rua Francisco Degni, CP 355, Araraquara SP 14801-907 (Brazil)], E-mail: elson@iq.unesp.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: derl@power.ufscar.br

    2009-05-05

    For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm{sup -1} and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

  20. Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

    International Nuclear Information System (INIS)

    Camargo, Emerson R.; Barrado, Cristiano M.; Ribeiro, Caue; Longo, Elson; Leite, Edson R.

    2009-01-01

    For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm -1 and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

  1. Applicability of Al-powder-alloy coating to corrosion barriers of 316SS in liquid lead-bismuth eutectic

    International Nuclear Information System (INIS)

    Kurata, Yuji; Sato, Hidetomo; Yokota, Hitoshi; Suzuki, Tetsuya

    2011-01-01

    A new Al-alloy coating method using Al, Ti and Fe powders has been applied to 316SS in order to develop corrosion resistant coating in liquid lead-bismuth eutectic (LBE). The 316SS plates with coating layers of different Al concentrations were exposed to liquid LBE with controlled oxygen concentrations of 10 -6 to 10 -4 mass% at 823 K for 3600 ks. While surface oxidation and grain boundary corrosion accompanied by liquid LBE penetration are observed in 316SS without Al-alloy coating, the Al-alloy coating is effective to protect such severe corrosion attacks in liquid LBE. Although the coating layer containing 2.8 mass% Al does not always keep sufficient corrosion resistance, good corrosion resistance is obtained through the Al-oxide film formed in liquid LBE in the coating layer where the average Al concentration is 4.2 mass%. Cracks are formed in the coating layer containing 17.8 mass% Al during the coating process. The Al-powder-alloy coating applied to 316SS is promising as a corrosion resistant coating method in liquid LBE environment. (author)

  2. Composition dependence of the ferroelectric properties of lanthanum-modified bismuth titanate thin films grown by using pulsed-laser deposition

    CERN Document Server

    Bu, S D; Park, B H; Noh, T W

    2000-01-01

    Lanthanum-modified bismuth titanate, Bi sub 4 sub - sub x La sub x Ti sub 3 O sub 1 sub 2 (BLT), thin films with a La concentration of 0.25<=x<=1.00 were grown on Pt/Ti/SiO sub 2 /Si substrates by using pulsed-laser deposition. The BLT films showed well-saturated polarization-electric field curves whose remnant polarizations were 16.1 mu C/cm sup 2 , 27.8 mu C/cm sup 2 , 19.6 mu C/cm sup 2 , and 2.7 mu C/cm sup 2 , respectively, for x=0.25, 0.05, 0.75, and 1.00. The fatigue characteristics became better with increasing x up to 0.75. The Au/BLT/Pt capacitor with a La concentration of 0.50 showed an interesting dependence of the remanent polarization on the number of repetitive read/write cycles. On the other hand, the capacitor with a La concentration of 0.75 showed fatigue-free characteristics.

  3. Formation of barium strontium titanate powder by solid state reaction using different calcination temperatures

    International Nuclear Information System (INIS)

    Teoh Wah Tzu; Ahmad Fauzi Mohd Noor; Zainal Arifin Ahmad

    2002-01-01

    The unique electrical properties of large permittivity in Barium Strontium Titanate have been widely used to make capacitors; it can be produced by solid state reaction. In this study, the mixture of Barium Carbonate, Strontium Carbonate and Titanium Dioxide was calcined at 500 degree C, 1000 degree C, 1100 degree C , 1150 degree C, 1200 degree C, 1250 degree C and 1300 degree C. The results of the phases change in each stage were investigated via X ay Diffraction. The results show that the formation of Barium Strontium Titanate started at 1100 degree C with the presence of other phases. The mixture is fully reacted to form Barium Strontium Titanate at 1150 degree C. Only Barium Strontium Titanate was formed as the calcination temperature was set higher. (Author)

  4. Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining

    International Nuclear Information System (INIS)

    Andrade, M.C.; Assis, J.T.; Pereira, F.R.

    2009-01-01

    A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO 3 formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

  5. Thermal stabilities of electromechanical properties in cobalt-modified strontium bismuth titanate (SrBi{sub 4}Ti{sub 4}O{sub 15})

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qian; Cao, Zhao-Peng; Wang, Chun-Ming, E-mail: wangcm@sdu.edu.cn; Fu, Qing-Wei; Yin, De-Fu; Tian, Hu-He

    2016-07-25

    Bismuth layer-structured ferroelectric (BLSF) strontium bismuth titanate (SrBi{sub 4}Ti{sub 4}O{sub 15}, SBT) ceramic oxides with B-site cobalt substitutions have been synthesized using conventional solid–state reaction. The dielectric, piezoelectric, and ferroelectric properties of cobalt-modified SBT are investigated in detail. The results indicate that cobalt is very effective in promoting the piezoelectric performance of SBT. The SBT modified with 3 mol% Co{sup 3+} (SBT-3Co) exhibits the optimized piezoelectric properties, with a piezoelectric constant d{sub 33} of 28 pC/N, which is the highest value among the modified SBT-based piezoelectric ceramics ever reported. The temperature-dependent electrical impedance, resonance frequencies, and electromechanical coupling factors (k{sub p} and k{sub t}) reveal that the cobalt-modified SBT ceramics have good thermal stabilities of electromechanical properties up to 300 °C. These results demonstrate that the cobalt-modified SBT ceramics are promising materials for high temperature piezoelectric sensors applications. - Graphical abstract: The manuscript deals with the thermal stabilities of piezoelectric properties of cobalt-modified SrBi{sub 4}Ti{sub 4}O{sub 15} (SBT) ceramics. The 3 mol% Co{sup 3+} modified SBT (SBT-3Co) ceramics exhibit a piezoelectric constant d{sub 33} of 28 pC/N and a Curie temperature T{sub c} of 528 °C. The SBT-3Co ceramics have good thermal stabilities of electromechanical properties up to 300 °C. - Highlights: • A high level of piezoelectric performance (d{sub 33}∼28 pC/N)is obtained. • High Curie temperature (T{sub c}∼528 °C) is acquired for the optimal composition. • The SBT-3Co exhibits good thermal stabilities of electromechanical properties. • The Co-modified SrBi{sub 4}Ti{sub 4}O{sub 15} is promising as high temperature piezoelectric material.

  6. Preparation of titanium oxide and metal titanates as powders, thin films, and microspheres by complex sol-gel process

    International Nuclear Information System (INIS)

    Deptula, A.; Olczak, T.; Lada, W.; Chmielewski, A.G.; Jakubaszek, U.; Sartowska, B.; Goretta, K.C.; Alvani, C.; Casadio, S.; Contini, V.

    2006-01-01

    Titanium oxide, for many years an important pigment, has recently been applied widely as a photocatalyst or as supports for metallic catalysts, gas sensors, photovoltaic solar cells, and water and air purification devices. Titanium oxide (TiO 2 ) and titanates based on Ba, Sr and Ca were prepared from commercial solutions of TiCl 4 and HNO 3 . The main preparation steps for the sols consisted of elimination of Cl - by distillation with HNO 3 and addition of metal hydroxides for the titanates. Resulting sols were gelled and used to: (a) prepare irregularly shaped powders by evaporation; (b) produce by a dipping technique thin films on glass, Ag or Ti supports; (c) produce spherical powders (diameters <100 μm) by solvent extraction. Results of thermal and X-ray-diffraction analyses indicated that the temperatures required to form the various compounds were lower than those necessary to form the compounds by conventional solid-state reactions and comparable to those required with use of organometallic based sol-gel methods. Temperatures of formation could be further reduced by addition of ascorbic acid (ASC) to the sols

  7. Magnetic properties of Aurivillius lanthanide-bismuth (LnFeO3nBi4Ti3O12 (n = 1,2 layered titanates

    Directory of Open Access Journals (Sweden)

    Tartaj, J.

    2008-06-01

    Full Text Available Bismuth titanates of Aurivillius layer-structure (BiFeO3nBi4Ti3O12, are of great technological interest because of their applications as non-volatile ferroelectric memories and high-temperature piezoelectric materials. The synthesis and crystallographic characterization of a new family of compounds (LnFeO3nBi4Ti3O12 was recently reported, in which the layers consist of LnFeO3 perovskites with a lanthanide Ln3+ substituting diamagnetic Bi3+. We report herein the magnetic properties of bulk samples, with Ln = Nd, Eu, Gd and Tb, and n = 1 and 2. Single-layer materials are paramagnetic, similar to non-substituted bismuth titanate Bi5FeTi3O15, and show crystal field effects due to the crystallographic environment of Eu3+ and Tb3+. Several anomalies are detected in the magnetization M(T of double-layer (LnFeO32Bi4Ti3O12 compounds, related to the strong magnetism of Tb and Gd, since they weakly appear for Nd and they are absent in the VanVleck Eu3+ ion and in the parent Bi6Fe2Ti3O18 compound.Los titanatos de hierro y bismuto con estructura laminar tipo Aurivillius, (BiFeO3nBi4Ti3O12, tienen un gran interés tecnológico debido a sus aplicaciones como memorias ferroeléctricas no volátiles y como piezoeléctrico cerámico de alta temperatura. La síntesis y la caracterización cristalina de una nueva familia de compuestos (LnFeO3nBi4Ti3O12 han sido recientemente reportadas, en la que el catión diamagnético Bi3+ ha sido sustituido por los paramagnéticos Ln3+ en los bloques de perovskita. Se estudian las propiedades magnéticas de muestras cerámicas en volumen con Ln = Nd, Eu, Gd y Tb, y n = 1 y 2. Los materiales con n=1 son paramagnéticos y similares al no sustituido Bi5FeTi3O15, y muestran efectos de campo cristalino debido al entorno cristalino de Eu3+ y Tb3+. Se han detectado algunas anomalías en la magnetización M(T de los compuestos n=2 (LnFeO32Bi4Ti3O12 que están relacionadas con el fuerte magnetismo de Tb y Gd, que aparecen d

  8. Study of Maxwell–Wagner (M–W) relaxation behavior and hysteresis observed in bismuth titanate layered structure obtained by solution combustion synthesis using dextrose as fuel

    International Nuclear Information System (INIS)

    Subohi, Oroosa; Shastri, Lokesh; Kumar, G.S.; Malik, M.M.; Kurchania, Rajnish

    2014-01-01

    Graphical abstract: X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T c ) to be 650 °C. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample. - Highlights: • Bi 4 Ti 3 O 12 is synthesized using solution combustion technique with dextrose as fuel. • Dextrose has high reducing capacity (+24) and generates more no. of moles of gases. • Impedance studies show that the sample follows Maxwell–Wagner relaxation behavior. • Shows lower remnant polarization due to higher c-axis ratio. - Abstract: Structural, dielectric and ferroelectric properties of bismuth titanate (Bi 4 Ti 3 O 12 ) obtained by solution combustion technique using dextrose as fuel is studied extensively in this paper. Dextrose is used as fuel as it has high reducing valancy and generates more number of moles of gases during the reaction. X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T c ) to be 650 °C. The dielectric loss is very less (tan δ < 1) at lower temperatures but increases around T c due to structural changes in the sample. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample

  9. Surface quality analysis of die steels in powder-mixed electrical discharge machining using titan powder in fine machining

    Directory of Open Access Journals (Sweden)

    Banh Tien Long

    2016-06-01

    Full Text Available Improving the quality of surface molds after electrical discharge machining is still being considered by many researchers. Powder-mixed dielectric in electrical discharge machining showed that it is one of the processing methods with high efficiency. This article reports on the results of surface quality of mold steels after powder-mixed electrical discharge machining using titanium powder in fine machining. The process parameters such as electrode material, workpiece material, electrode polarity, pulse on-time, pulse off-time, current, and titanium powder concentration were considered in the research. These materials are most commonly used with die-sinking electrical discharge machining in the manufacture of molds and has been selected as the subject of research: workpiece materials were SKD61, SKT4, and SKD11 mold steels, and electrode materials were copper and graphite. Taguchi’s method is used to design experiments. The influence of the parameters on surface roughness was evaluated through the average value and ratio (S/N. Results showed that the parameters such as electrical current, electrode material, pulse on-time, electrode polarity, and interaction between the electrode materials with concentration powder mostly influence surface roughness and surface roughness at optimal parameters SRopt = 1.73 ± 0.39 µm. Analysis of the surface layer after powder-mixed electrical discharge machining using titanium powder in optimal conditions has shown that the white layer with more uniform thickness and increased hardness (≈861.0 HV, and amount and size of microscopic cracks, is reduced. This significantly leads to the increase in the quality of the surface layer.

  10. Effects of surrounding powder in sintering process on the properties of Sb and Mn- doped barium-strontium titanate PTCR ceramics

    Directory of Open Access Journals (Sweden)

    Pornsuda Bomlai

    2006-05-01

    Full Text Available In this research, the effects of surrounding powder used during sintering of Sb and Mn doped bariumstrontium titanate (BST ceramics were studied. The ceramic samples were prepared by a conventional mixed-oxide method and placed on different powders during sintering. Phase formation, microstructure and PTCR behavior of the samples were then observed. Microstructures and PTCR behavior varied with the type of surrounding powder, whereas the crystal structure did not change. The surrounding powder has more effects on the shape of the grain than on the size. The grain size of samples was in the range of 5-20 μm. The most uniform grain size and the highest increase of the ratio of ρmax/ρRT were found to be about 106 for samples which had been sintered on Sb-doped BST powder. This value was an order of magnitude greater than for samples sintered on a powder of the equivalent composition to that of the sample pellet.

  11. X-band EPR studies of ferroelectric lead titanate (PT), piezoelectric lead magnesium niobate (PMN), and PMN/PT powders at 10 and 85 K

    International Nuclear Information System (INIS)

    Huang, J.; Fitzgerald, J.J.; Chasteen, N.D.

    1998-01-01

    X-band EPR spectra of lead titanate (PT) and lead magnesium niobate (PMN) powders prepared by different synthetic methods and a PMN/PT powder of the composition 0.9 PMN/01 PT were obtained at 85 and 10 K. Several EPR signals due to adventitious Fe 3+ ion impurities, a signal due to the Ti 3+ ion, and a signal due to the Pb 3+ ion are observed for PT, PMN, and PMN/PT powders. The EPR signals observed at g = 2.0 and 6.0 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of lad titanate with axial symmetry. The EPR signals observed at g = 1.99 and 4.25 are assigned to Fe 3+ ions in the B-sites of the perovskite lattice structure of PMN and 0.9 PMN/0.1 PT materials with cubic and rhombic symmetries, respectively. The sharp EPR signal observed at g = 1.94 is assigned to Ti 3= ion for PT and 0.9 PMN/0.1 PT powders. In addition, a broader EPR signal at g = 2.28--2.30 for PMN obtained by the molten salt method is assigned to axial Pb 3+ ion sites in this PMN material. EPR results obtained here for the e 3+ ions in the B-sites of the PMN materials, in particular, suggest that both cubic and rhombic symmetry sites corresponding to a range of Nb(OMg) x (ONb) 6-x site configurations exist in the PMN. These EPR results indicate that PMN likely exists with partial B-site cation (Mg/Nb) ordering in the perovskite lattice structure

  12. Comparative study of A-site order in the lead-free bismuth titanates M1/2Bi1/2TiO3 (M=Li, Na, K, Rb, Cs, Ag, Tl) from first-principles

    International Nuclear Information System (INIS)

    Gröting, Melanie; Albe, Karsten

    2014-01-01

    We investigate the possibility of enhancing chemical order in the relaxor ferroelectric Na 1/2 Bi 1/2 TiO 3 upon substitution of Na + by other monovalent cations M + using total energy calculations based on density functional theory. All chemically available monovalent cations M + , which are Li, Na, Ag, K, Tl, Rb and Cs, are considered and an analysis of the structurally relaxed structures in terms of symmetry-adapted distortion modes is given in order to quantify the chemically induced structural distortions. We demonstrate that the replacement of Na + by other monovalent cations can hardly alter the tendency of chemical order with respect to Na 1/2 Bi 1/2 TiO 3 . Only Tl 1/2 Bi 1/2 TiO 3 and Ag 1/2 Bi 1/2 TiO 3 show enhanced tendency for chemical ordering. Both heavy metals behave similar to the light alkali metals in terms of structural relaxations and relative stabilities of the ordered configurations. Although a comparison of the Goldschmidt factors of components (M TiO 3 ) − reveals for Tl a value above the upper stability limit for perovskites, the additional lone-pair effect of Tl + stabilizes the ordered structure. - Graphical abstract: Amplitudes of chemically induced distortion modes in different ordered perovskites M 1/2 Bi 1/2 TiO 3 and visualisation of atomic displacements associated with distortion mode X + 1 in the 001-ordered compounds Li 1/2 Bi 1/2 TiO 3 and Cs 1/2 Bi 1/2 TiO 3 . Due to a substantial size mismatch between bismuth (green) and caesium (dark blue), incorporation of the latter leads to enhanced displacements of oxygen atoms (red) and suppresses displacements of titanium (silver) as compared to lithium (light blue) or other smaller monovalent cations. - Highlights: • Lead-free A-site mixed bismuth titanates M 1/2 Bi 1/2 TiO 3 are studied by first-principles calculations. • Investigation of chemical ordering tendency for M=Li, Na, K, Rb, Cs, Ag, and Tl. • Group theoretical analysis of different ordered structures. • Ag and Tl

  13. Study on the Key Technology of High Purity Strontium Titanate Powder Synthesized from Oxalic Acid Co-sediment Precipitation

    Science.gov (United States)

    Bi, Xiaoguo; Dong, Yingnan; Li, Yingjie; Niu, Wei; Tang, Jian; Ding, Shuang; Li, Meiyang

    2017-09-01

    Oxalate coprecipitation is applied in this paper, high purity titanium tetrachloride, and after the purification of strontium chloride, match with a certain concentration of solution, oxalate and strontium chloride and titanium tetrachloride in 1.005:1.000 make strontium titanium mixture ratio, slowly under 60°C to join in oxalic acid solution, aging around 4 h, get oxygen titanium strontium oxalate (SrTiO(C2O4)2 • 4H2 ) precipitation, after washing, drying and other process made oxygen titanium strontium oxalate powder.

  14. Flame spray synthesis under a non-oxidizing atmosphere: Preparation of metallic bismuth nanoparticles and nanocrystalline bulk bismuth metal

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Robert N.; Stark, Wendelin J. [Institute for Chemical and Bioengineering, ETH Zuerich (Switzerland)], E-mail: wendelin.stark@chem.ethz.ch

    2006-10-15

    Metallic bismuth nanoparticles of over 98% purity were prepared by a modified flame spray synthesis method in an inert atmosphere by oxygen-deficient combustion of a bismuth-carboxylate based precursor. The samples were characterized by X-ray diffraction, thermal analysis and scanning electron microscopy confirming the formation of pure, crystalline metallic bismuth nanoparticles. Compression of the as-prepared powder resulted in highly dense, nanocrystalline pills with strong electrical conductivity and bright metallic gloss.

  15. Thickness dependence of the poling and current-voltage characteristics of paint films made up of lead zirconate titanate ceramic powder and epoxy resin

    Science.gov (United States)

    Egusa, Shigenori; Iwasawa, Naozumi

    1995-11-01

    A specially prepared paint made up of lead zirconate titanate (PZT) ceramic powder and epoxy resin was coated on an aluminum plate and was cured at room temperature, thus forming the paint film of 25-300 μm thickness with a PZT volume fraction of 53%. The paint film was then poled at room temperature, and the poling behavior was determined by measuring the piezoelectric activity as a function of poling field. The poling behavior shows that the piezoelectric activity obtained at a given poling field increases with an increase in the film thickness from 25 to 300 μm. The current-voltage characteristic of the paint film, on the other hand, shows that the increase in the film thickness leads not only to an increase in the magnitude of the current density at a given electric field but also to an increase in the critical electric field at which the transition from the ohmic to space-charge-limited conduction takes place. This fact indicates that the amount of the space charge of electrons injected into the paint film decreases as the film thickness increases. Furthermore, comparison of the current-voltage characteristic of the paint film with that of a pure epoxy film reveals that the space charge is accumulated largely at the interface between the PZT and epoxy phases in the paint film. On the basis of this finding, a model is developed for the poling behavior of the paint film by taking into account a possible effect of the space-charge accumulation and a broad distribution of the electric field in the PZT phase. This model is shown to give an excellent fit to the experimental data of the piezoelectric activity obtained here as a function of poling field and film thickness.

  16. Solid-phase extraction of galloyl- and caffeoylquinic acids from natural sources (Galphimia glauca and Arnicae flos) using pure zirconium silicate and bismuth citrate powders as sorbents inside micro spin columns.

    Science.gov (United States)

    Hussain, Shah; Schönbichler, Stefan A; Güzel, Yüksel; Sonderegger, Harald; Abel, Gudrun; Rainer, Matthias; Huck, Christian W; Bonn, Günther K

    2013-10-01

    Galloyl- and caffeoylquinic acids are among the most important pharmacological active groups of natural compounds. This study describes a pre-step in isolation of some selected representatives of these groups from biological samples. A selective solid-phase extraction (SPE) method for these compounds may help assign classes and isomer designations within complex mixtures. Pure zirconium silicate and bismuth citrate powders (325 mesh) were employed as two new sorbents for optimized SPE of phenolic acids. These sorbents possess electrostatic interaction sites which accounts for additional interactions for carbon acid moieties as compared to hydrophilic and hydrophobic sorbents alone. Based on this principle, a selective SPE method for 1,3,4,5-tetragalloylquinic acid (an anti-HIV and anti-asthamatic agent) as a starting compound was developed and then deployed upon other phenolic acids with success. The recoveries and selectivities of both sorbents were compared to most commonly applied and commercially available sorbents by using high performance liquid chromatography. The nature of interaction between the carrier sorbent and the acidic target molecules was investigated by studying hydrophilic (silica), hydrophobic (C18), mixed-mode (ionic and hydrophobic: Oasis(®) MAX) and predominantly electrostatic (zirconium silicate) materials. The newly developed zirconium silicate and bismuth citrate stationary phases revealed promising results for the selective extraction of galloyl- and caffeoylquinic acids from natural sources. It was observed that zirconium silicate exhibited maximum recovery and selectivity for tetragalloylquinic acid (84%), chlorogenic acid (82%) and dicaffeoylquinic acid (94%) among all the tested sorbents. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Ceria and strontium titanate based electrodes

    DEFF Research Database (Denmark)

    2010-01-01

    A ceramic anode structure obtainable by a process comprising the steps of: (a) providing a slurry by dispersing a powder of an electronically conductive phase and by adding a binder to the dispersion, in which said powder is selected from the group consisting of niobium-doped strontium titanate......, vanadium-doped strontium titanate, tantalum-doped strontium titanate, and mixtures thereof, (b) sintering the slurry of step (a), (c) providing a precursor solution of ceria, said solution containing a solvent and a surfactant, (d) impregnating the resulting sintered structure of step (b...

  18. Improvement of conditions for ceramics sintering on the base of lead zirconate-titanate

    International Nuclear Information System (INIS)

    Glinchuk, M.D.; Kim, P.V.; Bykov, I.P.; Lyashchenko, A.B.

    1989-01-01

    Lead zirconate-titanate powders of different graininess are studied for their phase composition. The finest grains of the powder consist of lead zirconate-titanate with the rhombohedral structure. Grains of 3-5 μm size are a mixture of lead zirconate-titanate and lead titanate, the latter exceeding 50% (by weight) causes the effect of anomalous expansion in the process of sintering. Control of the technological parameters of the synthesis permits producing powder with favourable correlation of the above phases and grain sizes. Sintering of such a powder induces no effect of the anomalous expansion with an increased density of the product attained

  19. Photoelectrochemical Properties of FeO Supported on TiO2-Based Thin Films Converted from Self-Assembled Hydrogen Titanate Nanotube Powders

    Directory of Open Access Journals (Sweden)

    Kyung-Jong Noh

    2012-01-01

    Full Text Available A photoanode was fabricated using hematite (α-Fe2O3 nanoparticles which had been held in a thin film of hydrogen titanate nanotubes (H-TiNT, synthesized by repetitive self-assembling method on FTO (fluorine-doped tin oxide glass, which were incorporated via dipping process in aqueous Fe(NO33 solution. Current voltage (I-V electrochemical properties of the photoanode heat-treated at 500°C for 10 min in air were evaluated under ultraviolet-visible light irradiation. Microstructure and crystallinity changes were also investigated. The prepared Fe2O3/H-TiNT/FTO composite thin film exhibited about threefold as much photocurrent as the Fe2O3/FTO film. The improvement in photocurrent was considered to be caused by reduced recombination of electrons and holes, with an appropriate amount of Fe2O3 spherical nanoparticles supported on the H-TiNT/FTO film. Nanosized spherical Fe2O3 particles with about 65 wt% on the H-TiNT/FTO film showed best performance in our study.

  20. Valley polarization in bismuth

    Science.gov (United States)

    Fauque, Benoit

    2013-03-01

    The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

  1. Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining; Caracterizacao do po de titanato de bario dopado com ions sodio e potasio com o refinamento de Rietveld

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, M.C.; Assis, J.T.; Pereira, F.R., E-mail: mcalixto@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Araujo, J.C. [Universidade do Estado do Rio de Janeiro (FFP/UERJ), Sao Goncalo, RJ (Brazil). Fac. de Formacao de Professores; Moreira, E.L.; Moraes, V.C.A.; Lopes, A.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO{sub 3} formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

  2. The mechanochemical stability of hydrogen titanate nanostructures

    International Nuclear Information System (INIS)

    Plodinec, M.; Friscic, I.; Ivekovic, D.; Tomasic, N.; Su, D.S.; Zhang, J.; Gajovic, A.

    2010-01-01

    The structural stability of some nanostructured titanates was investigated in terms of their subsequent processing and possible applications. With the aim to investigate their mechanochemical stability, we applied high-energy ball milling and studied the resulting induced phase transitions. Hydrogen titanates with two different morphologies, microcrystals and nanotubes, were taken into consideration. The phase-transition sequence was studied by Raman spectroscopy and X-ray powder diffraction, while the morphology and crystal structure, on the nanoscale, were analyzed by high-resolution transmission electron microscopy. During the mechanochemical treatment of both morphologies, the phase transitions from hydrogen titanate to TiO 2 anatase and subsequently to TiO 2 rutile were observed. In the case of hydrogen trititanate crystals, the phase transition to anatase starts after a longer milling time than in the case of the titanate nanotubes, which is explained by the larger particle size of the crystalline powder. However, the phase transition from anatase to rutile occurred more quickly in the crystalline powder than in the case of the nanotubes.

  3. Titan Aerial Daughtercraft

    Data.gov (United States)

    National Aeronautics and Space Administration — Saturn's giant moon Titan has become one of the most fascinating bodies in the Solar System. Titan is the richest laboratory in the solar system for studying...

  4. Titanic: A Statistical Exploration.

    Science.gov (United States)

    Takis, Sandra L.

    1999-01-01

    Uses the available data about the Titanic's passengers to interest students in exploring categorical data and the chi-square distribution. Describes activities incorporated into a statistics class and gives additional resources for collecting information about the Titanic. (ASK)

  5. Bismuth toxicity in patients treated with bismuth iodoform paraffin packs.

    Science.gov (United States)

    Atwal, A; Cousin, G C S

    2016-01-01

    Bismuth is a heavy metal used in bismuth iodoform paraffin paste (BIPP) antiseptic dressings and in a number of other medical preparations. It can be absorbed systemically and cause toxicity. We report 2 cases of such neurotoxicity after it was used in operations on the jaws. Copyright © 2015. Published by Elsevier Ltd.

  6. Texture and anisotropy in the bismuth sodium titanate system

    Science.gov (United States)

    Fancher, Christoher M.

    Bi0.5Na0.5TiO3 has received interest as a potential replacement for lead containing ferroelectrics. However, the piezoelectric response of pure Bi0.5Na0.5TiO 3 does not compare to the strong piezoelectric response of lead based piezoelectrics. To increase the piezoelectric response, Bi0.5Na 0.5TiO3 has been alloyed with BaTiO3 and K 0.5Na0.5NbO3. Another route to enhance the response is to take advantage of the anisotropic properties by inducing a preferred crystallographic orientation. Both routes were used to investigate the effect a crystallographic texture has on the strain response of Bi0.5Na 0.5TiO3-based ceramics. A crystallographic texture was induced by templated grain growth of pure phase Bi0.5Na0.5TiO3 templates using the tape casting method to orient template particles relative to the tape cast normal. Sintered Bi0.5Na0.5TiO3-based materials developed a strong (00l)pc fiber texture relative to the tape cast normal, with no preferential alignment relative to the tape cast plane. Textured Bi0.5Na0.5TiO3-(5)BaTiO3 showed a piezoelectric response of 245 pC/N, a better than 50% enhancement from the 150 pC/N response of randomly oriented samples. The Bi0.5Na0.5TiO3-(5)BaTiO3-(2)K 0.5Na0.5NbO3 (x,y) system has been shown to undergo electric-field-induced phase transformation from a pseudocubic to polar phase. For (7,2) a strong 8.7 multiples of a random distribution (MRD) crystallographic texture increased the macroscopic strain response by 50%. Applying the electric field perpendicular to the fiber texture axis reduces the macroscopic strain response of textured (7,2) by 17%. The affect field direction has on the electric-field-induced phase transformations of textured (7,2) was investigated using in situ electric field dependent diffraction. In situ diffraction data showed the high strain response of textured (7,2) can be attributed to a reversible pseudocubic to tetragonal transformation. The field-induced tetragonal phase nucleates preferentially with a strong c-axis alignment in the electric field direction, ferroelastic domain texture. In situ diffraction data suggests the origin of the reduction in strain associated with a field applied perpendicular to the fiber texture axis is the result of a shorter induced lattice spacing and lower domain texture.

  7. A study on structural stability of bismuth titanate with lanthanum ...

    Indian Academy of Sciences (India)

    2017-05-13

    May 13, 2017 ... such as high leakage current and domain pinning, which leads to small remanent ... (La(NO3)3 · 6H2O) were dissolved in distilled water for 2 h with constant ... a thermocouple (K-type, maximum detection at 1200. ◦. C). The.

  8. Process for fabricating mixed-oxide powders

    International Nuclear Information System (INIS)

    Elmaleh, D.; Giraudel, A.

    1975-01-01

    A physical-chemical process for fabricating homogeneous powders suitable for sintering is described. It can be applied to the synthesis of all mixed oxides having mutually compatible and water soluble salts. As a specific example, the fabrication of lead titanate-zirconate powders used to make hot pressed ceramics is described. These ceramics show improved piezoelectric properties [fr

  9. Barium titanate thick films prepared by screen printing technique

    Directory of Open Access Journals (Sweden)

    Mirjana M. Vijatović

    2010-06-01

    Full Text Available The barium titanate (BaTiO3 thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i pure, ii doped with lanthanum and iii doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed.

  10. Coating compositions comprising bismuth-alloyed zinc

    DEFF Research Database (Denmark)

    2008-01-01

    The present application discloses (i) a coating composition comprising a particulate zinc-based alloyed material, said material comprising 0.05-0.7% by weight of bismuth (Bi), the D50 of the particulate material being in the range of 2.5-30 µm; (ii) a coated structure comprising a metal structure...... having a first coating of the zinc-containing coating composition applied onto at least a part of the metal structure in a dry film thickness of 5-100 µm; and an outer coating applied onto said zinc-containing coating in a dry film thickness of 30-200 µm; (iii) a particulate zinc-based alloyed material......, wherein the material comprises 0.05-0.7%(w/w) of bismuth (Bi), and wherein the D50 of the particulate material is in the range of 2.5-30 µm; (iv) a composite powder consisting of at least 25%(w/w) of the particulate zinc-based alloyed material, the rest being a particulate material consisting of zinc...

  11. Radiation stability of sodium titanate ion exchange materials

    International Nuclear Information System (INIS)

    Kenna, B.T.

    1980-02-01

    Sodium titanate and sodium titanate loaded macroreticular resin are being considered as ion exchangers to remove 90 Sr and actinides from the large volume of defense waste stored at Hanford Site in Washington. Preliminary studies to determine the radiation effect on Sr +2 and I - capacity of these ion-exchange materials were conducted. Samples of sodium titanate powder, sodium titanate loaded macroreticular resin, as well as the nitrate form of macroreticular anion resin were irradiated with up to 2 x 10 9 Rads of 60 Co gamma rays. Sodium titanate cation capacity decreased about 50% while the sodium titanate loaded macroeticular resin displayed a dramatic decrease in cation capacity when irradiated with 10 8 -10 9 Rad. The latter decrease is tentatively ascribed to radiation damage to the organic portion which subsequently inhibits interaction with the contained sodium titanate. The anion capacity of both macroreticular resin and sodium titanate loaded macroreticular resin exhibited significant decreases with increasing radiation exposure. These results suggest that consideration should be given to the potential effects of radiation degradation if column regeneration is to be used. 5 figures, 2 tables

  12. Synthesis and characterization of superconducting bismuthates

    International Nuclear Information System (INIS)

    Tang, Horngyi.

    1991-01-01

    A new electrosynthetic technique for low-temperature crystal growth of superconducting bismuthates was developed, and its utility demonstrated by growing various high-quality BiO 3 crystals. The crystals of Ba 1-x K x BiO 3 and Ba 1-x Rb x BiO 3 display their T c onset at 31.8k and 28k, respectively, using SQUID magnetometry. The structure of a KBiO 3 x H 2 O single crystal determined by single crystal x-ray diffraction confirms previous results from powder samples that it is isostructural with KSbO 3 . The crystals of Ba 1-x Cs x BiO 3 do not show superconductivity to 4k. Chemical vapor-transport experiments leading to the fabrication of MoS 2 /WSe 2 junctions were also performed and are described in detail

  13. Niobium-doped strontium titanates as SOFC anodes

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Kammer Hansen, Kent; Wallenberg, L. Reine

    2008-01-01

    been synthesized with a recently developed modified glycine-nitrate process. The synthesized powders have been calcined and sintered in air or in 9% H(2) / N(2) between 800 - 1400 degrees C. After calcination the samples were single phase Nb-doped strontium titanate with grain sizes of less than 100 nm...... in diameter on average. The phase purity, defect structure, and microstructure of the materials have been analyzed with SEM, XRD, and TGA. The electrical conductivity of the Nb-doped titanate decreased with increasing temperature and showed a phonon scattering conduction mechanism with sigma > 120 S...... ability of the Nb-doped titanates to be used as a part of a SOFC anode. However, the catalytic activity of the materials was not sufficient and it needs to be improved if titanate based materials are to be realized as constituents in SOFC anodes....

  14. Effects of hydrothermal post-treatment on microstructures and morphology of titanate nanoribbons

    International Nuclear Information System (INIS)

    Yu Huogen; Yu Jiaguo; Cheng Bei; Zhou Minghua

    2006-01-01

    Titanate nanoribbons were prepared via a hydrothermal treatment of rutile-type TiO 2 powders in a 10 M NaOH solution at 200 deg. C for 48 h. The as-prepared titanate nanoribbons were then hydrothermally post-treated at 150 deg. C for 12-36 h. The titanate nanoribbons before and after hydrothermal post-treatment were characterized with FESEM, XRD, TEM, UV-VIS and nitrogen adsorption-desorption isotherms. The results showed that the hydrothermal post-treatment not only promoted the phase transformation from titanate to anatase TiO 2 , but also was beneficial to the removal of Na + ions remained in the titanate nanoribbons. After hydrothermal post-treatment, the TiO 2 samples retained the one-dimensional structure feature of the titanate nanoribbons and showed an obvious increase in the specific surface area and the pore volume

  15. Titan's organic chemistry

    Science.gov (United States)

    Sagan, C.; Thompson, W. R.; Khare, B. N.

    1985-01-01

    Voyager discovered nine simple organic molecules in the atmosphere of Titan. Complex organic solids, called tholins, produced by irradiation of the simulated Titanian atmosphere, are consistent with measured properties of Titan from ultraviolet to microwave frequencies and are the likely main constituents of the observed red aerosols. The tholins contain many of the organic building blocks central to life on earth. At least 100-m, and possibly kms thicknesses of complex organics have been produced on Titan during the age of the solar system, and may exist today as submarine deposits beneath an extensive ocean of simple hydrocarbons.

  16. NANOCOVERING OF TITAN WITH SILICON AND MOLYBDENUM AS ACTIVATOR OF FORMATION AND REACTIONARY AGGLOMERATION OF FILTERS AND MEMBRANES

    Directory of Open Access Journals (Sweden)

    V. N. Kovalevski

    2014-01-01

    Full Text Available The technology of production of porous powder materials with frame structure on the basis of spherical particles of titan powder by means of applying on them technological coverings (Si + Mo + C with the thickness up to 2 mm is developed. Formation of powders with covering was carried out in the mold at pressure below yield point (up to 150 MPa.

  17. Titan Casts Revealing Shadow

    Science.gov (United States)

    2004-05-01

    A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in

  18. Raising the Titanic.

    Science.gov (United States)

    Baker, Romona

    1990-01-01

    Described is an activity in which groups of students investigate engineering principles by writing a feasibility study to raise the luxury liner, Titanic. The problem statement and directions, and suggestions for problem solutions are included. (CW)

  19. Shape-controlled solvothermal synthesis of bismuth subcarbonate nanomaterials

    International Nuclear Information System (INIS)

    Cheng Gang; Yang Hanmin; Rong Kaifeng; Lu Zhong; Yu Xianglin; Chen Rong

    2010-01-01

    Much effort has been devoted to the synthesis of novel nanostructured materials because of their unique properties and potential applications. Bismuth subcarbonate ((BiO) 2 CO 3 ) is one of commonly used antibacterial agents against Helicobacter pylori (H. pylori). Different (BiO) 2 CO 3 nanostructures such as cube-like nanoparticles, nanobars and nanoplates, were fabricated from bismuth nitrate via a simple solvothermal method. The nanostructures were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). It was found that the solvents and precursors have an influence on the morphologies of (BiO) 2 CO 3 nanostructures. The possible formation mechanism of different (BiO) 2 CO 3 nanostructures fabricated under different conditions was also discussed. - Graphical abstract: Different bismuth subcarbonate ((BiO) 2 CO 3 ) nanostructures were successfully synthesized by a simple solvothermal method. It was found that the solvents and precursors have an influence on the morphologies of (BiO) 2 CO 3 nanostructures.

  20. Clash of the Titans

    Science.gov (United States)

    Subramaniam, Karthigeyan

    2010-01-01

    WebQuests and the 5E learning cycle are titans of the science classroom. These popular inquiry-based strategies are most often used as separate entities, but the author has discovered that using a combined WebQuest and 5E learning cycle format taps into the inherent power and potential of both strategies. In the lesson, "Clash of the Titans,"…

  1. Titan's Ammonia Feature

    Science.gov (United States)

    Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

    2011-01-01

    NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

  2. The TITAN reversed-field-pinch fusion reactor study

    International Nuclear Information System (INIS)

    1990-01-01

    This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures

  3. The TITAN reversed-field-pinch fusion reactor study

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This report discusses the following topics: overview of titan-2 design; titan-2 fusion-power-core engineering; titan-2 divertor engineering; titan-2 tritium systems; titan-2 safety design and radioactive-waste disposal; and titan-2 maintenance procedures.

  4. Giant energy density and high efficiency achieved in bismuth ferrite-based film capacitors via domain engineering.

    Science.gov (United States)

    Pan, Hao; Ma, Jing; Ma, Ji; Zhang, Qinghua; Liu, Xiaozhi; Guan, Bo; Gu, Lin; Zhang, Xin; Zhang, Yu-Jun; Li, Liangliang; Shen, Yang; Lin, Yuan-Hua; Nan, Ce-Wen

    2018-05-08

    Developing high-performance film dielectrics for capacitive energy storage has been a great challenge for modern electrical devices. Despite good results obtained in lead titanate-based dielectrics, lead-free alternatives are strongly desirable due to environmental concerns. Here we demonstrate that giant energy densities of ~70 J cm -3 , together with high efficiency as well as excellent cycling and thermal stability, can be achieved in lead-free bismuth ferrite-strontium titanate solid-solution films through domain engineering. It is revealed that the incorporation of strontium titanate transforms the ferroelectric micro-domains of bismuth ferrite into highly-dynamic polar nano-regions, resulting in a ferroelectric to relaxor-ferroelectric transition with concurrently improved energy density and efficiency. Additionally, the introduction of strontium titanate greatly improves the electrical insulation and breakdown strength of the films by suppressing the formation of oxygen vacancies. This work opens up a feasible and propagable route, i.e., domain engineering, to systematically develop new lead-free dielectrics for energy storage.

  5. Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huanwen [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Hu Zhongai, E-mail: zhongai@nwnu.edu.c [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2010-12-01

    This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 {sup o}C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g{sup -1} (based on composite) is obtained at a specific current of 1 A g{sup -1} as compared with 71 F g{sup -1} for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g{sup -1} even at 10 A g{sup -1}. In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

  6. Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

    International Nuclear Information System (INIS)

    Wang Huanwen; Hu Zhongai; Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying

    2010-01-01

    This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 o C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g -1 (based on composite) is obtained at a specific current of 1 A g -1 as compared with 71 F g -1 for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g -1 even at 10 A g -1 . In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

  7. Titan Polar Landscape Evolution

    Science.gov (United States)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  8. Titan Orbiter Aerorover Mission

    Science.gov (United States)

    Sittler Jr., E. C.; Acuna, M.; Burchell, M. J.; Coates, A.; Farrell, W.; Flasar, M.; Goldstein, B. E.; Gorevan, S.; Hartle, R. E.; Johnson, W. T. K.

    2001-01-01

    We propose a combined Titan orbiter and Titan Aerorover mission with an emphasis on both in situ and remote sensing measurements of Titan's surface, atmosphere, ionosphere, and magnetospheric interaction. The biological aspect of the Titan environment will be emphasized by the mission (i.e., search for organic materials which may include simple organics to 'amono' analogues of amino acids and possibly more complex, lightening detection and infrared, ultraviolet, and charged particle interactions with Titan's surface and atmosphere). An international mission is assumed to control costs. NASA will provide the orbiter, launch vehicle, DSN coverage and operations, while international partners will provide the Aerorover and up to 30% of the cost for the scientific instruments through collaborative efforts. To further reduce costs we propose a single PI for orbiter science instruments and a single PI for Aerorover science instruments. This approach will provide single command/data and power interface between spacecraft and orbiter instruments that will have redundant central DPU and power converter for their instruments. A similar approach could be used for the Aerorover. The mission profile will be constructed to minimize conflicts between Aerorover science, orbiter radar science, orbiter radio science, orbiter imaging science, and orbiter fields and particles (FP) science. Additional information is contained in the original extended abstract.

  9. Iodine Gas Trapping using Granular Porous Bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jae Hwan; Shin, Jin Myeong; Park, Jang Jin; Park, Geun Il [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Yim, Mansung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    {sup 129}I is a radionuclide with a very long half-life of 1.57 Χ 10{sup 7} years and has negative health effects to the human body. Therefore, the emission of {sup 129}I into the air is closely regulated by the Environmental Protection Agency (EPA). Many methods for trapping gaseous {sup 129}I have been developed thus far, including wet scrubbing and adsorption using silver loaded zeolites. Although wet scrubbing can effectively remove iodine, it suffers from corrosion of the vessel due to high concentration of the scrubbing solution. Silver loaded zeolites also show effectiveness in capturing {sup 129}I gas, yet weak thermal stability of physisorbed iodine remains a challenge. We studied a novel and facile method to trap iodine gas using bismuth. Granular bismuth having many pores was synthesized using bismuth nitrate and polyvinyl alcohol as a bismuth precursor and pore forming agent, respectively. Reaction of iodine and our samples resulted in an iodine capturing capacity of more than 2 times that of the commercial grade silver exchanged zeolite (AgX). Granular porous bismuths synthesized using bismuth nitrate and PVA show a promising performance in capturing iodine gas. The use of bismuth in trapping {sup 129}I gas can reduce the process cost as bismuth is cheap. Further study is going on to improve the mechanical property of granular porous bismuths for their easy handling.

  10. Iodine Gas Trapping using Granular Porous Bismuth

    International Nuclear Information System (INIS)

    Yang, Jae Hwan; Shin, Jin Myeong; Park, Jang Jin; Park, Geun Il; Yim, Mansung

    2014-01-01

    129 I is a radionuclide with a very long half-life of 1.57 Χ 10 7 years and has negative health effects to the human body. Therefore, the emission of 129 I into the air is closely regulated by the Environmental Protection Agency (EPA). Many methods for trapping gaseous 129 I have been developed thus far, including wet scrubbing and adsorption using silver loaded zeolites. Although wet scrubbing can effectively remove iodine, it suffers from corrosion of the vessel due to high concentration of the scrubbing solution. Silver loaded zeolites also show effectiveness in capturing 129 I gas, yet weak thermal stability of physisorbed iodine remains a challenge. We studied a novel and facile method to trap iodine gas using bismuth. Granular bismuth having many pores was synthesized using bismuth nitrate and polyvinyl alcohol as a bismuth precursor and pore forming agent, respectively. Reaction of iodine and our samples resulted in an iodine capturing capacity of more than 2 times that of the commercial grade silver exchanged zeolite (AgX). Granular porous bismuths synthesized using bismuth nitrate and PVA show a promising performance in capturing iodine gas. The use of bismuth in trapping 129 I gas can reduce the process cost as bismuth is cheap. Further study is going on to improve the mechanical property of granular porous bismuths for their easy handling

  11. Investigations of the Structure of Titanate Nanoscrolls

    International Nuclear Information System (INIS)

    Sheppard, D.A.; Buckley, C.E.

    2005-01-01

    Full text: Nanosized materials have attracted much research lately due to their unique properties and their potential application in nanoelectronic and optoelectronic devices. Nanostructured materials have also sparked interest as possible hydrogen storage candidates. Research at Curtin University has shown titanate nanoscrolls to absorb modest amounts of hydrogen at low temperatures. Whether or not this capacity can be improved will be dependent on a thorough understanding of the structure and the way it interacts with hydrogen. Titanate nanoscrolls are made via a soft chemical process that involves ageing TiO 2 powder in a concentrated NaOH solution. The resultant nanoscrolls, once filtered and washed, are typically 8-10 nm in diameter and hundreds of nanometers long. The walls consist of 3-5 layers and the diameter of the hollow centre is typically 5 nm. A number of different structures have been assigned to nanoscrolls produced via the soft chemical process. These include anatase, H 2 Ti 3 O 7 , lepidocrocite-type structure and H 2 Ti 4 O 9 .H 2 O. Many of these structures are similar, consisting of titanate type layers, and qualitatively reproduce the X-ray diffraction data. However, preliminary data suggests that these structures are inconsistent with neutron diffraction data. Here we attempt a more quantitative analysis of the structure than those published previously using neutron and X-ray diffraction. (authors)

  12. Oxygen depletion of bismuth molybdates

    Energy Technology Data Exchange (ETDEWEB)

    Yong, L.K.; Howe, R.F.; Keulks, G.W.; Hall, W.K.

    1978-05-01

    Pure ..cap alpha..-phase bismuth molybdate (Bi/sub 2/Mo/sub 3/O/sub 12/), which is known to be weakly active for selective oxidation, and pure ..gamma..-phase bismuth molybdate (Bi/sub 2/MoO/sub 6/), which has good activity, were subjected to oxidation-reduction cycles with known amounts of hydrogen and oxygen, at 300/sup 0/-570/sup 0/C and with evacuation steps between treatments. The volume of oxygen consumed during reoxidation was equal to half the hydrogen consumed during the reduction on the ..cap alpha..-phase, which indicated that no hydrogen was retained during reduction. For the ..gamma..-phase, the oxygen consumption was greater than half of the hydrogen consumption and it increased with extent of reduction. The excess oxygen was apparently consumed by filling anion vacancies formed during outgassing subsequent to the reduction step. ESR spectroscopy and temperature-programed oxidation-reduction indicated that lattice oxide ions which bridge between bismuth and molybdenum layers of the koechlinite structure become more labile when the catalyst is in a partially reduced state, and that this effect is greater in the ..gamma..- than the ..cap alpha..-phase. Table and 15 references.

  13. The tides of Titan.

    Science.gov (United States)

    Iess, Luciano; Jacobson, Robert A; Ducci, Marco; Stevenson, David J; Lunine, Jonathan I; Armstrong, John W; Asmar, Sami W; Racioppa, Paolo; Rappaport, Nicole J; Tortora, Paolo

    2012-07-27

    We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k(2) = 0.589 ± 0.150 and k(2) = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan's interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth.

  14. Bismuth absorption from sup 205 Bi-labelled pharmaceutical bismuth compounds used in the treatment of peptic ulcer disease

    Energy Technology Data Exchange (ETDEWEB)

    Dresow, B.; Fischer, R.; Gabbe, E.E.; Wendel, J.; Heinrich, H.C. (Eppendorf University Hospital, Hamburg (Germany))

    1992-04-01

    The absorption of bismuth from five {sup 205}Bi-labelled pharmaceutically used bismuth compounds was studied in man. From single oral doses of all compounds under investigation only <0.1% bismuth was absorbed and excreted with the urine. A significantly higher absorption was observed from the colloidal bismuth subcitrate and the basic bismuth gallate than from the basic bismuth salicylate, nitrate and aluminate. No retention of bismuth in the whole body was found from the single dose experiment. The biologic fast-term half-lives of absorbed bismuth were calculated to be 0.12 and 1.5 days. 14 refs., 2 figs., 1 tab.

  15. Diurnal variations of Titan

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  16. Thermogravimetric study of the kinetics of lithium titanate reduction by hydrogen

    International Nuclear Information System (INIS)

    Sonak, Sagar; Rakesh, R.; Jain, Uttam; Mukherjee, Abhishek; Kumar, Sanjay; Krishnamurthy, Nagaiyar

    2014-01-01

    Highlights: • Li 2 TiO 3 powder is synthesized by the gel combustion route. • Activation energy of reduction of Li 2 TiO 3 by H 2 found out to be 27.45 kJ/mol H 2 . • Non-stoichiometric phase of Li 2 TiO 3 is formed in hydrogen atmosphere. • One-dimensional diffusion appears to be the most probable mechanism of reduction. - Abstract: The lithium titanate powder was synthesized by gel-combustion route. The mechanism and the kinetics of hydrogen interaction with lithium titanate powder were studied using non-isothermal thermogravimetric technique. Lithium titanate underwent reduction in hydrogen atmosphere which led to the formation of oxygen deficient non-stoichiometric compound in lithium titanate. One-dimensional diffusion appeared to be the most probable reaction mechanism. The activation energy for reduction of lithium titanate under hydrogen atmosphere was found to be 27.4 kJ/mol/K. Structural changes after hydrogen reduction in lithium titanate were observed in X-ray diffraction analysis

  17. Experimental studies on 3D printing of barium titanate ceramics for medical applications

    Directory of Open Access Journals (Sweden)

    Schult Mark

    2016-09-01

    Full Text Available The present work deals with the 3D printing of porous barium titanate ceramics. Barium titanate is a biocompatible material with piezoelectric properties. Due to insufficient flowability of the starting material for 3D printing, the barium titanate raw material has been modified in three different ways. Firstly, barium titanate powder has been calcined. Secondly, flow additives have been added to the powder. And thirdly, flow additives have been added to the calcined powder. Finally, a polymer has been added to the three materials and specimens have been printed from these three material mixtures. The 3D printed parts were then sintered at 1320°C. The sintering leads to shrinkage which differs between 29.51–71.53% for the tested material mixtures. The porosity of the parts is beneficial for cell growth which is relevant for future medical applications. The results reported in this study demonstrate the possibility to fabricate porous piezoelectric barium titanate parts with a 3D printer that can be used for medical applications. 3D printed porous barium titanate ceramics can especially be used as scaffold for bone tissue engineering, where the bone formation can be promoted by electrical stimulation.

  18. Nanosized lithium titanates produced by plasma technique

    International Nuclear Information System (INIS)

    Grabis, J; Orlovs, A; Rasmane, Dz

    2007-01-01

    The synthesis of nanosized lithium titanates is studied by evaporation of coarse grained commercially available titanium and lithium carbonate particles in radio-frequency plasma flow with subsequent controlling formation and growth conditions of product particles. In accordance with the XRD analysis the phase composition of the obtained powders is determined by feeding rate of precursors and strongly by ratio of lithium and titanium. The Li 2 TiO 3 and Li 4 Ti 5 O 12 particles containing small amounts of extra phases were obtained at ratio of Li/Ti = 2 and Li/Ti = 0.8 respectively, feeding rate of precursors being in the range of 0.6-0.9 kg/h. Specific surface area of powders is in the range of 20-40 m2/g depending on concentration of vapours in gas flow and cooling rate of the products. Additional calcination of nanosize particles at 800-900 deg. C improves phase composition of lithium titanates

  19. Preparation and characterization of titanate nanotubes/carbon composites

    International Nuclear Information System (INIS)

    Wang Xiaodong; Pan Hui; Xue Xiaoxiao; Qian Junjie; Yu Laigui; Yang Jianjun; Zhang Zhijun

    2011-01-01

    Highlights: → Titanate nanotubes/carbon composites were synthesized from TiO 2 -carbon composites. → The carbon shell of TiO 2 particles obstructed the reaction between TiO 2 and NaOH. → TEM, XRD, and Raman spectra reveal the formation processes of the TNT/CCs. - Abstract: Titanate nanotubes/carbon composites(TNT/CCs) were synthesized by allowing carbon-coated TiO 2 (CCT) powder to react with a dense aqueous solution of NaOH at 120 deg. C for a proper period of time. As-prepared CCT and TNT/CCs were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectrometry. The processes for formation of titanate nanotubes/carbon composites were discussed. It was found that the TiO 2 particles in TiO 2 -carbon composite were enwrapped by a fine layer of carbon with a thickness of about 4 nm. This carbon layer functioned to inhibit the transformation from anatase TiO 2 to orthorhombic titanate. As a result, the anatase TiO 2 in CCT was incompletely transformed into orthorhombic titanate nanotubes upon 24 h of reaction in the dense and hot NaOH solution. When the carbon layers were gradually peeled off along with the formation of more orthorhombic titanate nanotubes at extended reaction durations (e.g., 72 h), anatase TiO 2 particles in CCT were completely transformed into orthorhombic titanate nanotubes, yielding TNT/CCs whose morphology was highly dependent on the reaction time and temperature.

  20. Outstanding visible photocatalytic activity of a new mixed bismuth titanatate material

    Energy Technology Data Exchange (ETDEWEB)

    Zambrano, P. [Instituto de Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, Americo Vespucio 49, 410092, Sevilla (Spain); Departamento Cristalografía, Mineralogía y Química Agrícola, Universidad de Sevilla, C/Profesor García González s/n, 41012 Sevilla (Spain); Sayagués, M.J.; Navío, J.A. [Instituto de Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, Americo Vespucio 49, 410092, Sevilla (Spain); Hidalgo, M.C., E-mail: carmen.hidalgo@csic.es [Instituto de Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, Americo Vespucio 49, 410092, Sevilla (Spain)

    2017-02-01

    Highlights: • Photocatalyst based on bismuth titanates with high visible activity. • Its visible activity as high as UV activity of TiO{sub 2} P25 for phenol degradation. • Photocatalyst is majority of phase Bi{sub 20}TiO{sub 32} with Bi{sub 4}Ti{sub 3}O{sub 12} and amorphous TiO{sub 2}. • High visible activity due to low BG, interconnected phases and high surface area. - Abstract: In this work, a new photocatalyst based on bismuth titanates with outstanding visible photocatalytic activity was prepared by a facile hydrothermal method. The synthesised material showed visible activity as high as UV activity of commercial TiO{sub 2} P25 under the same experimental conditions for phenol degradation. A wide characterisation of the photocatalyst was performed. The material was composed of three phases; majority of Bi{sub 20}TiO{sub 32} closely interconnected to Bi{sub 4}Ti{sub 3}O{sub 12} and amorphous TiO{sub 2}. The high visible activity showed by this material could be ascribed to a combination of several features; i.e. low band gap energy value (2.1 eV), a structure allowing a good separation path for visible photogenerated electron-holes pairs and a relatively high surface area. This photocatalyst appeared as a promising material for solar and visible applications of photocatalysis.

  1. Titan's icy scar

    Science.gov (United States)

    Griffith, C. A.; Penteado, P. F.; Turner, J. D.; Neish, C. D.; Mitri, G.; Montiel, M. J.; Schoenfeld, A.; Lopes, R. M. C.

    2017-09-01

    We conduct a Principal Components Analysis (PCA) of Cassini/VIMS [1] infrared spectral windows to identify and quantify weak surface features, with no assumptions on the haze and surface characteris- tics. This study maps the organic sediments, supplied by past atmospheres, as well as ice-rich regions that constitute Titan's bedrock.

  2. Use of titanates in decontamination of defense waste

    International Nuclear Information System (INIS)

    Dosch, R.G.

    1978-06-01

    Sodium titanate, an inorganic ion exchange material, has been evaluated for use in a process to remove strontium from Defense Waste or other high-sodium, caustic solutions. Distribution coefficients on the order of 10 5 were observed at sub part per million concentrations of Sr, and the effects of other cation impurities and complexants in the waste were investigated. The preparation and general chemical properties of the exchange material are discussed. This information was used in developing a commercial source which has since supplied a 200 kg batch of the material for evaluation. In column ion exchange experiments with 85 Sr-doped simulated waste, decontamination factors of 500 or greater were observed in the first 2000 to 3500 bed volumes of effluent, depending on the impurities in the simulant. A -40 to +130 mesh range of sodium titanate powder was used as the baseline material, but a study to produce alternate forms of the titanate was carried in parallel. This has resulted in two materials which appear promising with respect to both simplification of handling and chemical properties. One of the materials is an agglomerated form of the titanate formed by extrusion pelletizing using water as a binder, and the second is a macroreticular organic anion resin which was loaded with 30 to 40% (by weight) of sodium titanate. The results of initial testing of these materials are discussed

  3. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ratova, Marina, E-mail: marina_ratova@hotmail.com [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Kelly, Peter J.; West, Glen T. [Surface Engineering Group, School of Engineering, Manchester Metropolitan University, Manchester, M1 5GD (United Kingdom); Tosheva, Lubomira; Edge, Michele [School of Science and the Environment, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

    2017-01-15

    Highlights: • Bismuth tungstate coatings were deposited by reactive magnetron sputtering. • Oscillating bowl was introduced to the system to enable coating of nanopartulates. • Deposition of Bi{sub 2}WO{sub 6} enhanced visible light activity of titania nanoparticles. • The best results were obtained for coating with Bi:W ratio of approximately 2:1. • Deposition of Bi{sub 2}WO{sub 6} onto TiO{sub 2} resulted in more efficient electron-hole separation. - Abstract: Titanium dioxide − bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO{sub 2} evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO{sub 2} nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these

  4. Synthesis and characterization of titanium oxide/bismuth sulfide nanorods for solar cells applications

    International Nuclear Information System (INIS)

    Solis, M.; Rincon, M. E.

    2008-01-01

    In the present work is showed the synthesis and characterization of titanium oxide/bismuth sulfide nanowires hetero-junctions for solar cells applications. Conductive glass substrates (Corning 25 x 75 mm) were coated with a thin layer of sol-gel TiO2 and used as substrates for the subsequent deposition of bismuth sulfide nanorods (BN). TiO2 films (∼400 nm) were deposited with a semiautomatic immersion system with controlled immersion/withdraw velocity, using titanium isopropoxide as the titania precursor [1]. For BN synthesis and deposition, the solvo-thermal method was used, introducing air annealed TiO2-substrates in the autoclave. The typical bilayer TiO2/BN hetero-junction was 600 nm thick. The synthesized materials (powders and films) were characterized by X-Ray Diffraction, Scanning Electron Microscopy, and UV-Visible Spectroscopy. Anatase was the crystalline phase of TiO2, while bismuth sulfide nanotubes show a diffraction pattern characteristic of bismuthinite distorted by the preferential growth of some planes [2-4]. The optoelectronic characterization of TiO2/NB hetero-junctions was compared with hetero-junctions obtained by sensitizing TiO2 with chemically deposited bismuth sulfide films. Bismuth sulfide nanowires are 2µm long and 70nm wide (aspect ratio L/D = 43), while chemically deposited bismuth sulfide have L/D = 1, therefore the effect of particle size evaluation and geometry in the photosensitization phenomena will be discussed in the context of new materials for solar-cells applications. (Full text)

  5. Crystalline perfection and mechanical investigations on vertical Bridgman grown Bismuth telluride (Bi_2Te_3) single crystals for thermoelectric applications

    International Nuclear Information System (INIS)

    Krishna, Anuj; Vijayan, N.; Singh, Budhendra; Thukral, Kanika; Maurya, K.K.

    2016-01-01

    High efficiency thermoelectric materials plays a vital role in power generation and refrigeration applications. Bismuth telluride (Bi_2Te_3) is one among them. In the present work single crystal of bismuth telluride was grown using vertical Bridgman technique. The phase of grown crystals was analysed using a powder X-ray diffractometer. Quality of the grown crystal was assessed by using high resolution X-ray diffractometer and observed that it is fairly good. Further mechanical investigations on grown crystal was carried out using nano-indentation technique and various mechanical properties like hardness, stiffness and Young’s modulus were evaluated. Observed results clearly indicate its suitability for thermoelectric applications.

  6. On reactive suspension plasma spraying of calcium titanate

    OpenAIRE

    Kotlan, J. (Jiří); Pala, Z. (Zdeněk); Mušálek, R. (Radek); Ctibor, P. (Pavel)

    2016-01-01

    This study shows possibility of preparation of calcium titanate powder and coatings by reactive suspension plasma spraying. Suspension of mixture of calcium carbonate (CaCO3) and titanium dioxide (TiO2) powders in ethanol was fed into hybrid plasma torch with a DC-arc stabilized by a water–argon mixture (WSP-H 500). Various feeding distances and angles were used in order to optimize suspension feeding conditions. In the next step, the coatings were deposited on stainless steel substrates and ...

  7. Theoretical Investigation of Bismuth-Based Semiconductors for Photocatalytic Applications

    KAUST Repository

    Laradhi, Shaikhah

    2017-11-01

    Converting solar energy to clean fuel has gained remarkable attention as an emerged renewable energy resource but optimum efficiency in photocatalytic applications has not yet been reached. One of the dominant factors is designing efficient photocatalytic semiconductors. The research reveals a theoretical investigation of optoelectronic properties of bismuth-based metal oxide and oxysulfide semiconductors using highly accurate first-principles quantum method based on density functional theory along with the range-separated hybrid HSE06 exchange-correlation functional. First, bismuth titanate compounds including Bi12TiO20, Bi4Ti3O12, and Bi2Ti2O7 were studied in a combined experimental and theoretical approach to prove its photocatalytic activity under UV light. They have unique bismuth layered structure, tunable electronic properties, high dielectric constant and low electron and effective masses in one crystallographic direction allowing for good charge separation and carrier diffusion properties. The accuracy of the investigation was determined by the good agreement between experimental and theoretical values. Next, BiVO4 with the highest efficiency for oxygen evolution was investigated. A discrepancy between the experimental and theoretical bandgap was reported and inspired a systematic study of all intrinsic defects of the material and the corresponding effect on the optical and transport properties. A candidate defective structure was proposed for an efficient photocatalytic performance. To overcome the carrier transport limitation, a mild hydrogen treatment was also introduced. Carrier lifetime was enhanced due to a significant reduction of trap-assisted recombination, either via passivation of deep trap states or reduction of trap state density. Finally, an accurate theoretical approach to design a new family of semiconductors with enhanced optoelectronic properties for water splitting was proposed. We simulated the solid solutions Bi1−xRExCuOS (RE = Y, La

  8. Preparation and Characterization of Nano-structured Ceramic Powders Synthesized by Emulsion Combustion Method

    International Nuclear Information System (INIS)

    Takatori, Kazumasa; Tani, Takao; Watanabe, Naoyoshi; Kamiya, Nobuo

    1999-01-01

    The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia-ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10 nm. The zirconia-ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources

  9. Bismuth ions are metabolized into autometallographic traceable bismuth-sulphur quantum dots

    Directory of Open Access Journals (Sweden)

    M Stoltenberg

    2009-06-01

    Full Text Available Bismuth – sulphur quantum dots can be silver enhanced by autometallography (AMG. In the present study, autometallographic silver enhanced bismuth-sulphur nanocrystals were isolated from unfixed cryo-sections of kidneys and livers of rats exposed to bismuth (Bi207 subnitrate. After being subjected to AMG all the organic material was removed by sonication and enzymatic digestion and the silver enhanced Bi- S quantum dots spun down by an ultracentrifuge and analyzed by scintillation. The analysis showed that the autometallographic technique traces approximately 94% of the total bismuth. This implies that the injected bismuth is ultimately captured in bismuthsulphur quantum dots, i.e., that Bi-S nanocrystals are the end product of bismuth metabolism

  10. The preparation of a novel layered lead titanate and its conversion to the perovskite lead titanate PbTiO3

    NARCIS (Netherlands)

    Blake, G.R.; Armstrong, A.R.; Sastre, E.; Wright, P.A.

    2001-01-01

    A novel layered lead titanate with the approximate composition PbTiO2(CO3)0.3(NO3)0.35(OH) has been synthesized hydrothermally under acidic conditions. The structure has been solved and refined from X-ray and neutron powder diffraction data in the space group P -3 1 m, with cell dimensions a =

  11. Bismuth Silver Oxysulfide for Photoconversion Applications: Structural and Optoelectronic Properties

    KAUST Repository

    Baqais, Amal Ali Abdulallh; Curutchet, Antton; Ziani, Ahmed; Ait Ahsaine, Hassan; Sautet, Philippe; Takanabe, Kazuhiro; Le Bahers, Tangui

    2017-01-01

    Single-phase bismuth silver oxysulfide, BiAgOS, was prepared by a hydrothermal method. Its structural, morphological and optoelectronic properties were investigated and compared with bismuth copper oxysulfide (BiCuOS). Rietveld refinement of the powder X-ray diffraction (XRD) measurements revealed that the BiAgOS and BiCuOS crystals have the same structure as ZrSiCuAs: the tetragonal space group P4/nmm. X-ray photoelectron spectroscopy (XPS) analyses confirmed that the BiAgOS has a high purity, in contrast with BiCuOS, which tends to have Cu vacancies. The Ag has a monovalent oxidation state, whereas Cu is present in the oxidation states of +1 and +2 in the BiCuOS system. Combined with experimental measurements, density functional theory calculations employing the range-separated hybrid HSE06 exchange-correlation functional with spin-orbit coupling quantitatively elucidated photophysical properties such as ab-sorption coefficients, effective masses and dielectric constants. BiCuOS and BiAgOS were found to have indirect bandgaps of 1.1 and 1.5 eV, respectively. Both possess high dielectric constants and low electron and hole effective masses. Therefore, these materials are expected to have high exciton dissociation capabilities and excellent carrier diffusion properties. This study reveals that BiAgOS is a promising candidate for photoconversion applications.

  12. Bismuth Silver Oxysulfide for Photoconversion Applications: Structural and Optoelectronic Properties

    KAUST Repository

    Baqais, Amal Ali Abdulallh

    2017-09-18

    Single-phase bismuth silver oxysulfide, BiAgOS, was prepared by a hydrothermal method. Its structural, morphological and optoelectronic properties were investigated and compared with bismuth copper oxysulfide (BiCuOS). Rietveld refinement of the powder X-ray diffraction (XRD) measurements revealed that the BiAgOS and BiCuOS crystals have the same structure as ZrSiCuAs: the tetragonal space group P4/nmm. X-ray photoelectron spectroscopy (XPS) analyses confirmed that the BiAgOS has a high purity, in contrast with BiCuOS, which tends to have Cu vacancies. The Ag has a monovalent oxidation state, whereas Cu is present in the oxidation states of +1 and +2 in the BiCuOS system. Combined with experimental measurements, density functional theory calculations employing the range-separated hybrid HSE06 exchange-correlation functional with spin-orbit coupling quantitatively elucidated photophysical properties such as ab-sorption coefficients, effective masses and dielectric constants. BiCuOS and BiAgOS were found to have indirect bandgaps of 1.1 and 1.5 eV, respectively. Both possess high dielectric constants and low electron and hole effective masses. Therefore, these materials are expected to have high exciton dissociation capabilities and excellent carrier diffusion properties. This study reveals that BiAgOS is a promising candidate for photoconversion applications.

  13. Titanic exploration with GIS

    Science.gov (United States)

    Kerski, J.J.

    2004-01-01

    To help teachers and students investigate one of the world's most famous historical events using the geographic perspective and GIS tools and methods, the U.S. Geological Survey (USGS) created a set of educational lessons based on the RMS Titanic's April 1912 sailing. With these lessons, student researchers can learn about latitude and longitude, map projections, ocean currents, databases, maps, and images through the analysis of the route, warnings, sinking, rescue, and eventual discovery of the submerged ocean liner in 1985. They can also consider the human and physical aspects of the maiden voyage in the North Atlantic Ocean at a variety of scales, from global to regional to local. Likewise, their investigations can reveal how the sinking of the Titanic affected future shipping routes.

  14. Ethane ocean on Titan

    Science.gov (United States)

    Lunine, J. I.; Stevenson, D. J.; Yung, Y.L.

    1983-01-01

    Voyager I radio occultation data is employed to develop a qualitative model of an ethane ocean on Titan. It is suggested that the ocean contains 25 percent CH4 and that the ocean is in dynamic equilibrium with an N2 atmosphere. Previous models of a CH4 ocean are discounted due to photolysis rates of CH4 gas. Tidal damping of Titan's orbital eccentricity is taken as evidence for an ocean layer approximately 1 km deep, with the ocean floor being covered with a solid C2H2 layer 100 to 200 m thick. The photolytic process disrupting the CH4, if the estimates of the oceanic content of CH4 are correct, could continue for at least one billion years. Verification of the model is dependent on detecting CH4 clouds in the lower atmosphere, finding C2H6 saturation in the lower troposphere, or obtaining evidence of a global ocean.

  15. Organic chemistry on Titan

    Science.gov (United States)

    Chang, S.; Scattergood, T.; Aronowitz, S.; Flores, J.

    1979-01-01

    Features taken from various models of Titan's atmosphere are combined in a working composite model that provides environmental constraints within which different pathways for organic chemical synthesis are determined. Experimental results and theoretical modeling suggest that the organic chemistry of the satellite is dominated by two processes: photochemistry and energetic particle bombardment. Photochemical reactions of CH4 in the upper atmosphere can account for the presence of C2 hydrocarbons. Reactions initiated at various levels of the atmosphere by cosmic rays, Saturn 'wind', and solar wind particle bombardment of a CH4-N2 atmospheric mixture can account for the UV-visible absorbing stratospheric haze, the reddish appearance of the satellite, and some of the C2 hydrocarbons. In the lower atmosphere photochemical processes will be important if surface temperatures are sufficiently high for gaseous NH3 to exist. It is concluded that the surface of Titan may contain ancient or recent organic matter (or both) produced in the atmosphere.

  16. Landscape Evolution of Titan

    Science.gov (United States)

    Moore, Jeffrey

    2012-01-01

    Titan may have acquired its massive atmosphere relatively recently in solar system history. The warming sun may have been key to generating Titan's atmosphere over time, starting from a thin atmosphere with condensed surface volatiles like Triton, with increased luminosity releasing methane, and then large amounts of nitrogen (perhaps suddenly), into the atmosphere. This thick atmosphere, initially with much more methane than at present, resulted in global fluvial erosion that has over time retreated towards the poles with the removal of methane from the atmosphere. Basement rock, as manifested by bright, rough, ridges, scarps, crenulated blocks, or aligned massifs, mostly appears within 30 degrees of the equator. This landscape was intensely eroded by fluvial processes as evidenced by numerous valley systems, fan-like depositional features and regularly-spaced ridges (crenulated terrain). Much of this bedrock landscape, however, is mantled by dunes, suggesting that fluvial erosion no longer dominates in equatorial regions. High midlatitude regions on Titan exhibit dissected sedimentary plains at a number of localities, suggesting deposition (perhaps by sediment eroded from equatorial regions) followed by erosion. The polar regions are mainly dominated by deposits of fluvial and lacustrine sediment. Fluvial processes are active in polar areas as evidenced by alkane lakes and occasional cloud cover.

  17. Bio-assisted synthesis and characterization of nanostructured bismuth (III) sulphide using Clostridium acetobutylicum

    International Nuclear Information System (INIS)

    Kamaraj, Sathish Kumar; Venkatachalam, Ganesh; Arumugam, Palaniappan; Berchmans, Sheela

    2014-01-01

    Nanostructured bismuth (III) sulphide is synthesized at room temperature using a hydrogen sulphide producing microorganism namely Clostridium acetobutylicum. On contrary to chemical routes involving both the high and room temperature methods, the present experimental procedure involves a bio-assisted approach. This method is free from the usage of toxic and hazardous chemicals making it an environment friendly route. The synthesized bismuth sulphide is characterized using transmission electron microscope (TEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). From our experiments we find that bismuth sulphide produced using this bio-assisted approach exhibits a hexagonal shaped plate-like structures and is stabilized by the extracellular proteins present in the culture medium. - Graphical abstract: A green chemistry approach towards the synthesis of bismuth (III) sulphide nanostructures at room temperature using a hydrogen sulphide producing microorganism namely, Clostridium acetobutylicum is demonstrated. - Highlights: • Environmentally benign (greener) route towards synthesis of Bi 2 S 3 nanostructures. • Bio-assisted synthesis of Bi 2 S 3 at room temperature using Clostridium acetobutylicum. • Extracellular proteins in H 2 S producing microorganism as stabilizer for Bi 2 S 3 NPs. • Hexagonal platelets of Bi 2 S 3 possessing an orthorhombic crystalline structure

  18. Titan's methane clock

    Science.gov (United States)

    Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

    2010-04-01

    Measurements of the 12C/13C and D/H isotopic ratios in Titan's methane show intriguing differences from the values recorded in the giant planets. This implies that either (1) the atmosphere was differently endowed with material at the time of formation, or (2) evolutionary processes are at work in the moon's atmosphere - or some combination of the two. The Huygens Gas Chromatograph Mass Spectrometer Instrument (GCMS) found 12CH4/13CH4 = 82 +/- 1 (Niemann et al. 2005), some 7% lower than the giant planets' value of 88 +/- 7 (Sada et al. 1996), which closely matches the terrestrial inorganic standard of 89. The Cassini Composite Infrared Spectrometer (CIRS) has previously reported 12CH4/13CH4 of 77 +/-3 based on nadir sounding, which we now revise upwards to 80 +/- 4 based on more accurate limb sounding. The CIRS and GCMS results are therefore in agreement about an overall enrichment in 13CH4 of ~10%. The value of D/H in Titan's CH4 has long been controversial: historical measurements have ranged from about 8-15 x 10-5 (e.g. Coustenis et al. 1989, Coustenis et al. 2003). A recent measurement based on CIRS limb data by Bezard et al. (2007) puts the D/H in CH4 at (13 +/- 1) x 10-5, very much greater than in Jupiter and Saturn, ~2 x 10-5 (Mahaffy et al. 1998, Fletcher et al. 2009). To add complexity, the 12C/13C and D/H vary among molecules in Titan atmosphere, typically showing enhancement in D but depletion in 13C in the daughter species (H2, C2H2, C2H6), relative to the photochemical progenitor, methane. Jennings et al. (2009) have sought to interpret the variance in carbon isotopes as a Kinetic Isotope Effect (KIE), whilst an explanation for the D/H in all molecules remains elusive (Cordier et al. 2008). In this presentation we argue that evolution of isotopic ratios in Titan's methane over time forms a ticking 'clock', somewhat analogous to isotopic ratios in geochronology. Under plausible assumptions about the initial values and subsequent replenishment, various

  19. Titan after Cassini Huygens

    Science.gov (United States)

    Beauchamp, P. M.; Lunine, J.; Lebreton, J.; Coustenis, A.; Matson, D.; Reh, K.; Erd, C.

    2008-12-01

    In 2005, the Huygens Probe gave us a snapshot of a world tantalizingly like our own, yet frozen in its evolution on the threshold of life. The descent under parachute, like that of Huygens in 2005, is happening again, but this time in the Saturn-cast twilight of winter in Titan's northern reaches. With a pop, the parachute is released, and then a muffled splash signals the beginning of the first floating exploration of an extraterrestrial sea-this one not of water but of liquid hydrocarbons. Meanwhile, thousands of miles away, a hot air balloon, a "montgolfiere," cruises 6 miles above sunnier terrain, imaging vistas of dunes, river channels, mountains and valleys carved in water ice, and probing the subsurface for vast quantities of "missing" methane and ethane that might be hidden within a porous icy crust. Balloon and floater return their data to a Titan Orbiter equipped to strip away Titan's mysteries with imaging, radar profiling, and atmospheric sampling, much more powerful and more complete than Cassini was capable of. This spacecraft, preparing to enter a circular orbit around Saturn's cloud-shrouded giant moon, has just completed a series of flybys of Enceladus, a tiny but active world with plumes that blow water and organics from the interior into space. Specialized instruments on the orbiter were able to analyze these plumes directly during the flybys. Titan and Enceladus could hardly seem more different, and yet they are linked by their origin in the Saturn system, by a magnetosphere that sweeps up mass and delivers energy, and by the possibility that one or both worlds harbor life. It is the goal of the NASA/ESA Titan Saturn System Mission (TSSM) to explore and investigate these exotic and inviting worlds, to understand their natures and assess the possibilities of habitability in this system so distant from our home world. Orbiting, landing, and ballooning at Titan represent a new and exciting approach to planetary exploration. The TSSM mission

  20. Titan's Methane Cycle is Closed

    Science.gov (United States)

    Hofgartner, J. D.; Lunine, J. I.

    2013-12-01

    Doppler tracking of the Cassini spacecraft determined a polar moment of inertia for Titan of 0.34 (Iess et al., 2010, Science, 327, 1367). Assuming hydrostatic equilibrium, one interpretation is that Titan's silicate core is partially hydrated (Castillo-Rogez and Lunine, 2010, Geophys. Res. Lett., 37, L20205). These authors point out that for the core to have avoided complete thermal dehydration to the present day, at least 30% of the potassium content of Titan must have leached into an overlying water ocean by the end of the core overturn. We calculate that for probable ammonia compositions of Titan's ocean (compositions with greater than 1% ammonia by weight), that this amount of potassium leaching is achievable via the substitution of ammonium for potassium during the hydration epoch. Formation of a hydrous core early in Titan's history by serpentinization results in the loss of one hydrogen molecule for every hydrating water molecule. We calculate that complete serpentinization of Titan's core corresponds to the release of more than enough hydrogen to reconstitute all of the methane atoms photolyzed throughout Titan's history. Insertion of molecular hydrogen by double occupancy into crustal clathrates provides a storage medium and an opportunity for ethane to be converted back to methane slowly over time--potentially completing a cycle that extends the lifetime of methane in Titan's surface atmosphere system by factors of several to an order of magnitude over the photochemically-calculated lifetime.

  1. Microwave assisted synthesis and characterization of barium titanate nanoparticles for multi layered ceramic capacitor applications.

    Science.gov (United States)

    Thirumalai, Sundararajan; Shanmugavel, Balasivanandha Prabu

    2011-01-01

    Barium titanate is a common ferroelectric electro-ceramic material having high dielectric constant, with photorefractive effect and piezoelectric properties. In this research work, nano-scale barium titanate powders were synthesized by microwave assisted mechano-chemical route. Suitable precursors were ball milled for 20 hours. TGA studies were performed to study the thermal stability of the powders. The powders were characterized by XRD, SEM and EDX Analysis. Microwave and Conventional heating were performed at 1000 degrees C. The overall heating schedule was reduced by 8 hours in microwave heating thereby reducing the energy and time requirement. The nano-scale, impurity-free and defect-free microstructure was clearly evident from the SEM micrograph and EDX patterns. LCR meter was used to measure the dielectric constant and dielectric loss values at various frequencies. Microwave heated powders showed superior dielectric constant value with low dielectric loss which is highly essential for the fabrication of Multi Layered Ceramic Capacitors.

  2. Cryovolcanism on Titan

    Science.gov (United States)

    Mitri, G.; Showman, A. P.; Lunine, J. I.; Lopes, R. M.

    2008-12-01

    Remote sensing observations yield evidence for cryovolcanism on Titan, and evolutionary models support (but do not require) the presence of an ammonia-water subsurface ocean. The impetus for invoking ammonia as a constituent in an internal ocean and cryovolcanic magma comes from two factors. First, ammonia-water liquid has a lower freezing temperature than pure liquid water, enabling cryovolcanism under the low- temperature conditions prevalent in the outer Solar System. Second, pure water is negatively buoyant with respect to pure water ice, which discourages eruption from the subsurface ocean to the surface. In contrast, the addition of ammonia to the water decreases its density, hence lessening this problem of negative buoyancy. A marginally positive buoyant ammonia-water mixture might allow effusive eruptions from a subsurface ocean. If the subsurface ocean were positively buoyant, all the ammonia would have been erupted very early in Titan's history. Contrary to this scenario, Cassini-Huygens has so far observed neither a global abundance nor a complete dearth of cryovolcanic features. Further, an ancient cryovolcanic epoch cannot explain the relative youth of Titan's surface. Crucial to invoking ammonia-water resurfacing as the source of the apparently recent geological activity is not how to make ammonia-water volcanism work (because the near neutral buoyancy of the ammonia-water mixture encourages an explanation), but rather how to prevent eruption from occurring so easily that cryovolcanic activity is over early on. Although cryovolcanism by ammonia-water has been proposed as a resurfacing process on Titan, few models have specifically dealt with the problem of how to transport ammonia-water liquid onto the surface. We proposed a model of cryovolcanism that involve cracking at the base of the ice shell and formation of ammonia-water pockets in the ice. While the ammonia-water pockets cannot easily become neutral buoyant and promote effusive eruptions

  3. Gravimetric Analysis of Bismuth in Bismuth Subsalicylate Tablets: A Versatile Quantitative Experiment for Undergraduate Laboratories

    Science.gov (United States)

    Davis, Eric; Cheung, Ken; Pauls, Steve; Dick, Jonathan; Roth, Elijah; Zalewski, Nicole; Veldhuizen, Christopher; Coeler, Joel

    2015-01-01

    In this laboratory experiment, lower- and upper-division students dissolved bismuth subsalicylate tablets in acid and precipitated the resultant Bi[superscript 3+] in solution with sodium phosphate for a gravimetric determination of bismuth subsalicylate in the tablets. With a labeled concentration of 262 mg/tablet, the combined data from three…

  4. Acetylene on Titan

    Science.gov (United States)

    Singh, Sandeep; McCord, Thomas B.; Combe, Jean-Philippe; Rodriguez, Sebastien; Cornet, Thomas; Le Mouélic, Stéphane; Clark, Roger Nelson; Maltagliati, Luca; Chevrier, Vincent

    2016-10-01

    Saturn's moon Titan possesses a thick atmosphere that is mainly composed of N2 (98%), CH4 (2 % overall, but 4.9% close to the surface) and less than 1% of minor species, mostly hydrocarbons [1]. A dissociation of N2 and CH4 forms complex hydrocarbons in the atmsophere and acetylene (C2H2) and ethane (C2H6) are produced most abundently. Since years, C2H2 has been speculated to exist on the surface of Titan based on its high production rate in the stratosphere predicted by photochemical models [2,3] and from its detection as trace gas sublimated/evaporated from the surface after the landing of the Huygens probe by the Gas Chromatograph Mass Spectrometer (GCMS) [1]. Here we show evidence of acetylene (C2H2) on the surface of Titan by detecting absorption bands at 1.55 µm and 4.93 µm using Cassini Visual and Infrared Mapping Spectrometer (VIMS) [4] at equatorial areas of eastern Shangri-La, and Fensal-Aztlan/Quivira.An anti-correlation of absorption band strength with albedo indicates greater concentrations of C2H2 in the dark terrains, such as sand dunes and near the Huygens landing site. The specific location of the C2H2 detections suggests that C2H2 is mobilized by surface processes, such as surface weathering by liquids through dissolution/evaporation processes.References:[1]Niemann et al., Nature 438, 779-784 (2005).[2]Lavvas et al., Planetary and Space Science 56, 67 - 99 (2008).[3]Lavvas et al., Planetary and Space Science 56, 27 - 66 (2008).[4] Brown et al., The Cassini-Huygens Mission 111-168 (Springer, 2004).

  5. Titan's Radioactive Haze : Production and Fate of Radiocarbon On Titan

    Science.gov (United States)

    Lorenz, R. D.; Jull, A. J. T.; Swindle, T. D.; Lunine, J. I.

    Just as cosmic rays interact with nitrogen atoms in the atmosphere of Earth to gener- ate radiocarbon (14C), the same process should occur in Titan`s nitrogen-rich atmo- sphere. Titan`s atmosphere is thick enough that cosmic ray flux, rather than nitrogen column depth, limits the production of 14 C. Absence of a strong magnetic field and the increased distance from the sun suggest production rates of 9 atom/cm2/s, approx- imately 4 times higher than Earth. On Earth the carbon is rapidly oxidised into CO2. The fate and detectability of 14C on Titan depends on the chemical species into which it is incorporated in Titan's reducing atmosphere : as methane it would be hopelessly diluted even in only the atmosphere (ignoring the other, much more massive carbon reservoirs likely to be present on Titan, like hydrocarbon lakes.) However, in the more likely case that the 14C attaches to the haze that rains out onto the surface (as tholin, HCN or acetylene and their polymers - a much smaller carbon reservoir) , haze in the atmosphere or recently deposited on the surface would therefore be quite intrinsically radioactive. Such activity may modify the haze electrical charging and hence its coag- ulation. Measurements with compact instrumentation on future in-situ missions could place useful constraints on the mass deposition rates of photochemical material on the surface and identify locations where surface deposits of such material are `freshest`.

  6. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, Jean-Claude

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have...

  7. Titan's Gravitational Field

    Science.gov (United States)

    Schubert, G.; Anderson, J. D.

    2013-12-01

    Titan's gravitational field is inferred from an analysis of archived radio Doppler data for six Cassini flybys. The analysis considers each flyby separately in contrast to the approach of lumping all the data together in a massive inversion. In this way it is possible to gain an improved understanding of the character of each flyby and its usefulness in constraining the gravitational coefficient C22 . Though our analysis is not yet complete and our final determination of C22 could differ from the result we report here by 1 or 2 sigma, we find a best-fit value of C22 equal to (13.21 × 0.17) × 10-6, significantly larger than the value of 10.0 × 10-6 obtained from an inversion of the lumped Cassini data. We also find no determination of the tidal Love number k2. The larger value of C22 implies a moment of inertia factor equal to 0.3819 × 0.0020 and a less differentiated Titan than is suggested by the smaller value. The larger value of C22 is consistent with an undifferentiated model of the satellite. While it is not possible to rule out either value of C22 , we prefer the larger value because its derivation results from a more hands on analysis of the data that extracts the weak hydrostatic signal while revealing the effects of gravity anomalies and unmodeled spacecraft accelerations on each of the six flybys.

  8. Titan's Emergence from Winter

    Science.gov (United States)

    Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

    2011-01-01

    We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

  9. A FAMILY OF PEROXO-TITANATE MATERIALS TAILORED FOR OPTIMAL STRONTIUM ANDACTINIDE SORPTION

    International Nuclear Information System (INIS)

    Hobbs, D

    2006-01-01

    Achieving global optimization of inorganic sorbent efficacy, as well as tailoring sorbent specificity for target sorbates would facilitate increased wide-spread use of these materials in applications such as producing potable water or nuclear waste treatment. Sodium titanates have long been known as sorbents for radionuclides; 90 Sr and transuranic elements in particular. We have developed a related class of materials, which we refer to as peroxo-titanates: these are sodium titanates or hydrous titanates synthesized in the presence of or treated post-synthesis with hydrogen peroxide. Peroxo-titanates show remarkable and universal improved sorption behavior with respect to separation of actinides and strontium from Savannah River Site (SRS) nuclear waste simulants. Enhancement in sorption kinetics can potentially result in as much as an order of magnitude increase in batch processing throughput. Peroxo-titanates have been produced by three different synthetic routes: post-synthesis peroxide-treatment of a commercially produced monosodium titanate, an aqueous-peroxide synthetic route, and an isopropanol-peroxide synthetic route. The peroxo-titanate materials are characteristically yellow to orange, indicating the presence of protonated or hydrated Ti-peroxo species; and the chemical formula can be generally written as H v Na w Ti 2 O 5 -(xH 2 O)[yH z O 2 ] where (v+w) = 2, z = 0-2, and total volatile species accounts for 25-50 wt % of the solid. Further enhancement of sorption performance is achieved by processing, storing and utilizing the peroxo-titanate as an aqueous slurry rather than a dry powder, and post-synthesis acidification. All three synthesis modifications; addition of hydrogen peroxide, use of a slurry form and acidification can be applied more broadly to the optimization of other metal oxide sorbents and other ion separations processes

  10. Microwave absorption properties of barium titanate/epoxide resin composites

    International Nuclear Information System (INIS)

    Chen Xiaodong; Wang Guiqin; Duan Yuping; Liu Shunhua

    2007-01-01

    Nano-barium titanate (BT) was prepared by a sol-gel method. The prepared powders were characterized by x-ray powder diffraction and transmission electron microscopy. The complex relative dielectric permittivity (ε = ε' - jε-prime) and magnetic permeability (μ = μ' - jμ-prime) of the BT powders were measured in the frequency range 8 ∼ 18 GHz. The BT/epoxide resin (EP) composite with different volume contents was investigated. The effects of thickness on the BT/EP composite were studied. It was found that an optimum thickness and contents of the absorber can yield the maximum reflection loss which could be obtained over a broad frequency region in the X and Ku bands. Our results indicate that BT could be a promising microwave absorption material

  11. Electromagnetic properties of carbon black and barium titanate composite materials

    International Nuclear Information System (INIS)

    Wang Guiqin; Chen Xiaodong; Duan Yuping; Liu Shunhua

    2008-01-01

    Nanocrystalline carbon black/barium titanate compound particle (CP) was synthesized by sol-gel method. The phase structure and morphology of compound particle were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM) and Raman spectrum measurements, the electroconductivity was test by trielectrode arrangement and the precursor powder was followed by differential scanning calorimetric measurements (DSC) and thermal gravimetric analysis (TGA). In addition, the complex relative permittivity and permeability of compound particle were investigated by reflection method. The compound particle/epoxide resin composite (CP/EP) with different contents of CP were measured. The results show barium titanate crystal is tetragonal phase and its grain is oval shape with 80-100 nm which was coated by carbon black film. As electromagnetic (EM) complex permittivity, permeability and reflection loss (RL) shown that the compound particle is mainly a kind of electric and dielectric lossy materials and exhibits excellent microwave absorption performance in the X- and Ku-bands

  12. (YSZ) powders

    Indian Academy of Sciences (India)

    Unknown

    109–114. © Indian Academy of Sciences. 109 ... Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085, India .... pensions of 900°C calcined YSZ powders. .... The sintered density data of the compacts (sintered at.

  13. Short report: evaluation of Helicobacter pylori eradication with bismuth sucralfate

    NARCIS (Netherlands)

    Reijers, M. H.; Noach, L. A.; Tytgat, G. N.

    1994-01-01

    In a pilot study we have evaluated the clinical efficacy of bismuth sucralfate to eradicate H. pylori. Ten consecutive patients with chronic dyspepsia and H. pylori associated gastritis were treated with bismuth sucralfate (220 mg bismuth per tablet, 4 tablets per day for 4 weeks). If a 14C urea

  14. Synthesis and characterization of bismuth zinc niobate pyrochlore nanopowders

    Directory of Open Access Journals (Sweden)

    Sonia Maria Zanetti

    2007-09-01

    Full Text Available Bismuth zinc niobate pyrochlores Bi1.5ZnNb1.5O7 (alpha-BZN, and Bi2(Zn1/3Nb2/32O 7 (beta-BZN have been synthesized by chemical method based on the polymeric precursors. The pyrochlore phase was investigated by differential scanning calorimetry, infrared spectroscopy, and X ray diffraction. Powder and sintered pellets morphology was examined by scanning electron microscopy. The study of alpha-BZN phase formation reveals that, at 500 °C, the pyrochlore phase was already present while a single-phased nanopowder was obtained after calcination at 700 °C. The crystallization mechanism of the beta-BZN is quite different, occurring through the crystallization of alpha-BZN and BiNbO4 intermediary phases. Both compositions yielded soft agglomerated powders. alpha-BZN pellets, sintered at 800 °C for 2 hours, presented a relative density of 97.3% while those of beta-BZN, sintered at 900 °C for 2 hours, reached only 91.8%. Dielectric constant and dielectric loss, measured at 1 MHz, were 150 and 4 x/10-4 for a-BZN, and 97 and 8 x 10-4 for beta-BZN.

  15. Preparation and characterization of bismuth oxichloride (BiOCl) nanoparticles and nano zerovalent iron (nZVI)

    International Nuclear Information System (INIS)

    Sarwan, Bhawna; Pare, Brijesh; Acharya, Aman Deep

    2017-01-01

    In this work, we have synthesized nano scale zerovalent iron (nZVI) particles by borohydride reduction method and bismuth oxichloride (BiOCl) by a hydrolysis method. X-ray powder diffraction (XRD) was used for the structural and chemical characterization, while scanning/transmission electron microscopy (SEM/TEM) were employed to determine the physical properties of the nanoparticles. The reactivity of synthesized nanoparticles was compared by decolorization of nile blue (NB) dye under visible irradiation. (paper)

  16. Titan's greenhouse and antigreenhouse effects

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1992-01-01

    Thermal mechanisms active in Titan's atmosphere are discussed in a brief review of data obtained during the Voyager I flyby in 1980. Particular attention is given to the greenhouse effect (GHE) produced by atmospheric H2, N2, and CH4; this GHE is stronger than that on earth, with CH4 and H2 playing roles similar to those of H2O and CO2 on earth. Also active on Titan is an antigreenhouse effect, in which dark-brown and orange organic aerosols block incoming solar light while allowing IR radiation from the Titan surface to escape. The combination of GHE and anti-GHE leads to a surface temperature about 12 C higher than it would be if Titan had no atmosphere.

  17. Seasonal Changes in Titan's Meteorology

    Science.gov (United States)

    Turtle, E. P.; DelGenio, A. D.; Barbara, J. M.; Perry, J. E.; Schaller, E. L.; McEwen, A. S.; West, R. A.; Ray, T. L.

    2011-01-01

    The Cassini Imaging Science Subsystem has observed Titan for 1/4 Titan year, and we report here the first evidence of seasonal shifts in preferred locations of tropospheric methane clouds. South \\polar convective cloud activity, common in late southern summer, has become rare. North \\polar and northern mid \\latitude clouds appeared during the approach to the northern spring equinox in August 2009. Recent observations have shown extensive cloud systems at low latitudes. In contrast, southern mid \\latitude and subtropical clouds have appeared sporadically throughout the mission, exhibiting little seasonality to date. These differences in behavior suggest that Titan s clouds, and thus its general circulation, are influenced by both the rapid temperature response of a low \\thermal \\inertia surface and the much longer radiative timescale of Titan s cold thick troposphere. North \\polar clouds are often seen near lakes and seas, suggesting that local increases in methane concentration and/or lifting generated by surface roughness gradients may promote cloud formation. Citation

  18. Capture of toxic radioactive and heavy metal ions from water by using titanate nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jiasheng, E-mail: jiashengxu@bhu.edu.cn [Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds, College of Chemistry, Chemical Engineering and Food Safety, Center of Science and Technology Experiment, Bohai University, 19 Sci-tech Road, Jinzhou 121013 (China); Zhang, He; Zhang, Jie [Liaoning Province Key Laboratory for Synthesis and Application of Functional Compounds, College of Chemistry, Chemical Engineering and Food Safety, Center of Science and Technology Experiment, Bohai University, 19 Sci-tech Road, Jinzhou 121013 (China); Kim, Eui Jung [School of Chemical Engineering and Bioengineering, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

    2014-11-25

    Highlights: • Three types of titanate nanofibers were prepared via a hydrothermal porcess. • These nanofibers show availability for removal of the toxic ions from water. • The equilibrium data were fitted well with the Langmuir model. - Abstract: Three types of titanate nanofibers (sodium titanate nanofibers (TNF-A), potassium/sodium titanate nanofibers (TNF-B), potassium titanate nanofibers (TNF-C)) were prepared via a hydrothermal treatment of anatase powders in different alkali solutions at 170 °C for 96 h, respectively. The as-prepared nanofibers have large specific surface area and show availability for the removal of radioactive and heavy metal ions from water system, such as Ba{sup 2+} (as substitute of {sup 226}Ra{sup 2+}) and Pb{sup 2+} ions. The TNF-A shows a better capacity in the removal of Ba{sup 2+} and Pb{sup 2+} than TNF-B and TNF-C. Structural characterization of the materials was performed with powder X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and with inductively coupled plasma optical emission spectrometry (ICP-OES). It is found that the equilibrium data fit well with the Langmuir model. This study highlights that nanoparticles of inorganic ion exchangers with layered structure are potential materials for efficient removal of the toxic ions from contaminated water.

  19. The age of Titan's surface

    Science.gov (United States)

    Neish, C. D.; Lorenz, R. D.

    2010-04-01

    High-resolution images of the surface of Titan taken by the Cassini spacecraft reveal a world with an extreme paucity of impact craters. Planetary surfaces are commonly dated by dividing the number of impact craters by the estimated impactor flux, but this approach has been confounded at Titan by several difficulties. First, high-resolution imaging of the surface of Titan is far from complete (in the near-infrared as well as radar). As of December 2007, Cassini RADAR images covered only 22% of its surface. However, we can use Monte-Carlo models to explore how many craters of a given size (with large or very large craters being of particular interest) may be present in the unobserved areas. Second, literature descriptions of the crater formation rate (e.g. Korycansky and Zahnle 2005 and Artemieva and Lunine 2005) are apparently not in agreement. We discuss possible resolutions. Third, since surface modification processes are ongoing, the actual number of craters on Titan's surface remains uncertain, as craters may be eroded beyond recognition, or obscured by lakes or sand seas. In this connection, we use the Earth as an analogue. The Earth is in many ways the most "Titan-like" world in the solar system, with extensive modification by erosion, burial, tectonism, and volcanism. We compare the observed number of terrestrial craters to the expected terrestrial impactor flux to determine the crater reduction factor for a world similar to Titan. From this information, we can back out the actual number of craters on Titan's surface and estimate its crater retention age. An accurate age estimate will be critical for constraining models of Titan's formation and evolution.

  20. Monosodium titanate particle characterization

    International Nuclear Information System (INIS)

    Chandler, G.T.; Hobbs, D.T.

    1993-01-01

    A characterization study was performed on monosodium titanate (MST) particles to determine the effect of high shear forces expected from the In-Tank Precipitation (ITP) process pumps on the particle size distribution. The particles were characterized using particle size analysis and scanning electron microscopy (SEM). No significant changes in particle size distributions were observed between as-received MST and after 2--4 hours of shearing. Both as-received and sheared MST particles contained a large percentage of porosity with pore sizes on the order of 500 to 2,000 Angstroms. Because of the large percentage of porosity, the overall surface area of the MST is dominated by the internal surfaces. The uranium and plutonium species present in the waste solution will have access to both interior and exterior surfaces. Therefore, uranium and plutonium loading should not be a strong function of MST particle size

  1. Chemistry in Titan

    Science.gov (United States)

    Plessis, S.; Carrasco, N.; Pernot, P.

    2009-04-01

    Modelling the chemical composition of Titan's ionosphere is a very challenging issue. Latest works perform either inversion of CASSINI's INMS mass spectra (neutral[1] or ion[2]), or design coupled ion-neutral chemistry models[3]. Coupling ionic and neutral chemistry has been reported to be an essential feature of accurate modelling[3]. Electron Dissociative Recombination (EDR), where free electrons recombine with positive ions to produce neutral species, is a key component of ion-neutral coupling. There is a major difficulty in EDR modelling: for heavy ions, the distribution of neutral products is incompletely characterized by experiments. For instance, for some hydrocarbon ions only the carbon repartition is measured, leaving the hydrogen repartition and thus the exact neutral species identity unknown[4]. This precludes reliable deterministic modelling of this process and of ion-neutral coupling. We propose a novel stochastic description of the EDR chemical reactions which enables efficient representation and simulation of the partial experimental knowledge. The description of products distribution in multi-pathways reactions is based on branching ratios, which should sum to unity. The keystone of our approach is the design of a probability density function accounting for all available informations and physical constrains. This is done by Dirichlet modelling which enables one to sample random variables whose sum is constant[5]. The specifics of EDR partial uncertainty call for a hierarchiral Dirichlet representation, which generalizes our previous work[5]. We present results on the importance of ion-neutral coupling based on our stochastic model. C repartition H repartition (measured) (unknown ) → C4H2 + 3H2 + H .. -→ C4 . → C4H2 + 7H → C3H8. + CH C4H+9 + e- -→ C3 + C .. → C3H3 + CH2 + 2H2 → C2H6 + C2H2 + H .. -→ C2 + C2 . → 2C2H2 + 2H2 + H (1) References [1] J. Cui, R.V. Yelle, V. Vuitton, J.H. Waite Jr., W.T. Kasprzak

  2. Methane rain on Titan

    Science.gov (United States)

    Toon, Owen B.; Mckay, Christopher P.; Courtin, Regis; Ackerman, Thomas P.

    1988-01-01

    The atmosphere of Titan is characterized by means of model computations based on Voyager IRIS IR spectra and published data from laboratory determinations of absorption coefficients and cloud refractive indices. The results are presented in tables and graphs, and it is pointed out that the presence of Ar is not required in the model. Particular attention is given to the role of CH4, which is found to form patchy clouds (with particle radii of 50 microns or greater and visible/IR optical depths of 2-5) at altitudes up to about 30 km. The mechanisms by which such rain-sized particles could form are discussed, and it is suggested that the observed 500-600/cm spectrum is affected much less by the CH4 clouds than by H2 or variations in the temperature of the high-altitude haze.

  3. The TITAN reversed-field-pinch fusion reactor study

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures.

  4. The TITAN reversed-field-pinch fusion reactor study

    International Nuclear Information System (INIS)

    1990-01-01

    This report discusses research on the titan-1 fusion power core. The major topics covered are: titan-1 fusion-power-core engineering; titan-1 divertor engineering; titan-1 tritium systems; titan-1 safety design and radioactive-waste disposal; and titan-1 maintenance procedures

  5. Conventional hydrothermal synthesis of titanate nanotubes: Systematic discussions on structural, optical, thermal and morphological properties

    Directory of Open Access Journals (Sweden)

    S. Muniyappan

    2017-12-01

    Full Text Available Titanate nanotubes were successfully synthesized by hydrothermal technique under acidic-base medium. The anatase and titanate phase of the starting TiO2 and tubular titanate was confirmed by powder XRD technique. The UV–vis-NIR spectroscopy was used to study the absorption nature of titanate nanotubes and the band gap was calculated as 3.3 eV. Infrared technique was employed to detect the presence of all the functional groups in the synthesized titanate nanotube material. Thermal properties of the title material were studied by TG-DTA analyses. The shrinkage of interlayer distance of TiO2 network confirms the nanotube formation. Morphology and size information about the synthesized material were carried out using FESEM and TEM analysis. Titanate nanotubes are having the maximum length of 2.24 µm and the average diameter of 169.73 nm. EDX analysis gives out the elemental composition of the as synthesized product. This report may fetch an efficient way to synthesize TiO2 nanotubes using TiO2 nanoparticles.

  6. Bismuth Subgallate Toxicity in the Age of Online Supplement Use.

    Science.gov (United States)

    Sampognaro, Paul; Vo, Kathy T; Richie, Megan; Blanc, Paul D; Keenan, Kevin

    2017-11-01

    Bismuth salts have been used to treat gastroenterological disorders and are readily available over-the-counter and via the internet. Even though generally considered safe, bismuth compounds can cause a syndrome of subacute, progressive encephalopathy when taken in large quantities. We present the case of woman who developed progressive encephalopathy, aphasia, myoclonus, and gait instability after chronically ingesting large amounts of bismuth subgallate purchased from a major online marketing website to control symptoms of irritable bowel syndrome. After extensive neurological work-up, elevated bismuth levels in her blood, urine, and cerebrospinal fluid confirmed the diagnosis of bismuth-related neurotoxicity. She improved slowly following cessation of exposure. This case highlights bismuth subgallate as a neurotoxic bismuth formulation and reminds providers of the potential for safety misconceptions of positively reviewed online supplements.

  7. Performance of neutron activation analysis in the evaluation of bismuth iodide purification methodology

    International Nuclear Information System (INIS)

    Armelin, Maria Jose A.; Ferraz, Caue de Mello; Hamada, Margarida M.

    2015-01-01

    Bismuth tri-iodide (BrI 3 ) is an attractive material for using as a semiconductor. In this paper, BiI 3 crystals have been grown by the vertical Bridgman technique using commercially available powder. The impurities were evaluated by instrumental neutron activation analysis (INAA). The results show that INAA is an analytical method appropriate for monitoring the impurities of: Ag, As, Br, Cr, K, Mo, Na and Sb in the various stages of the BiI 3 purification methodology. (author)

  8. Titan Montgolfiere Terrestrial Test Bed, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. To better plan this mission and create a...

  9. Titan Montgolfiere Terrestrial Test Bed, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — With the Titan Saturn System Mission, NASA is proposing to send a Montgolfiere balloon to probe the atmosphere of Titan. In order to better plan this mission and...

  10. Radio-sensitization of animals by bismuth; Radio sensibilisation de l'animal par le bismuth

    Energy Technology Data Exchange (ETDEWEB)

    Pierotti, T; Verain, A [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Digestive absorption of bismuth by animals leads to radio-sensitization. This effect is very marked when the X-rays used are centered on the absorption line of bismuth. This work has involved the use of more than 2000 C3H/JAX mice, and has shown that a maximum lethal effect, with respect to the standard, occurs for bismuth sub-nitrate doses of the order of 3 g/kg and for exposures of 700 R. For stronger or weaker doses, the sensitization effect is less marked. (authors) [French] L'absorption digestive de bismuth provoque une radiosensibilisation de l'animal. Celle-ci est nette quand le rayonnement X utilise est centre sur la raie d'absorption du bismuth. L'etude portant sur plus de 2000 souris C3H/JAX a montre une lethalite maximale par rapport aux temoins pour des doses de sous-nitrate de bismuth de l'ordre de 3 g/kg et pour des expositions de 700 R. Pour des doses plus fortes ou plus faibles, l'effet de sensibilisation est moins net. (auteurs)

  11. The atmospheric temperature structure of Titan

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, J. B.; Courtin, Regis; Lunine, Jonathan I.

    1992-01-01

    The contribution of various factors to the thermal structure of Titan's past and present atmosphere are discussed. A one dimensional model of Titan's thermal structure is summarized. The greenhouse effect of Titan's atmosphere, caused primarily by pressure induced opacity of N2, CH4, and H2, is discussed together with the antigreenhouse effect dominated by the haze which absorbs incident sunlight. The implications for the atmosphere of the presence of an ocean on Titan are also discussed.

  12. 21 CFR 73.2110 - Bismuth citrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Bismuth citrate. 73.2110 Section 73.2110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... paragraph (c)(1), effective April 27, 2010. For the convenience of the user, the revised text is set forth...

  13. Magnetoreflection studies of ion implanted bismuth

    International Nuclear Information System (INIS)

    Nicolini, C.; Chieu, T.C.; Dresselhaus, M.S.; Massachusetts Inst. of Tech., Cambridge; Dresselhaus, G.

    1982-01-01

    The effect of the implantation of Sb ions on the electronic structure of the semimetal bismuth is studied by the magnetoreflection technique. The results show long electronic mean free paths and large implantation-induced increases in the band overlap and L-point band gap. These effects are opposite to those observed for Bi chemically doped with Sb. (author)

  14. Powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Hart, M.

    1995-12-31

    the importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940`s, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments.

  15. Powder diffraction

    International Nuclear Information System (INIS)

    Hart, M.

    1995-01-01

    The importance of x-ray powder diffraction as an analytical tool for phase identification of materials was first pointed out by Debye and Scherrer in Germany and, quite independently, by Hull in the US. Three distinct periods of evolution lead to ubiquitous application in many fields of science and technology. In the first period, until the mid-1940's, applications were and developed covering broad categories of materials including inorganic materials, minerals, ceramics, metals, alloys, organic materials and polymers. During this formative period, the concept of quantitative phase analysis was demonstrated. In the second period there followed the blossoming of technology and commercial instruments became widely used. The history is well summarized by Parrish and by Langford and Loueer. By 1980 there were probably 10,000 powder diffractometers in routine use, making it the most widely used of all x-ray crystallographic instruments. In the third, present, period data bases became firmly established and sophisticated pattern fitting and recognition software made many aspects of powder diffraction analysis routine. High resolution, tunable powder diffractometers were developed at sources of synchrotron radiation. The tunability of the spectrum made it possible to exploit all the subtleties of x-ray spectroscopy in diffraction experiments

  16. Powder diffractometry

    International Nuclear Information System (INIS)

    Doucet, J.

    1983-01-01

    The new possibilities openned by the synchrotron radiation in the powder diffractometry techniques are presented. This technique is described in a general manner and some aspects which can be developed with the use of the synchrotron radiation are analyzed. (L.C.) [pt

  17. Organic chemistry on Titan: Surface interactions

    Science.gov (United States)

    Thompson, W. Reid; Sagan, Carl

    1992-01-01

    The interaction of Titan's organic sediments with the surface (solubility in nonpolar fluids) is discussed. How Titan's sediments can be exposed to an aqueous medium for short, but perhaps significant, periods of time is also discussed. Interactions with hydrocarbons and with volcanic magmas are considered. The alteration of Titan's organic sediments over geologic time by the impacts of meteorites and comets is discussed.

  18. Disposable screen-printed bismuth electrode modified with multi-walled carbon nanotubes for electrochemical stripping measurements.

    Science.gov (United States)

    Niu, Xiangheng; Zhao, Hongli; Lan, Minbo

    2011-01-01

    Integrating the advantages of screen printing technology with the encouraging electroanalytical characteristic of metallic bismuth, we developed an ultrasensitive and disposable screen-printed bismuth electrode (SPBE) modified with multi-walled carbon nanotubes (MWCNTs) for electrochemical stripping measurements. Metallic bismuth powders and MWCNTs were homogeneously mixed with graphite-carbon ink to mass-prepare screen-printed bismuth electrode doped with multi-walled carbon nanotubes (SPBE/MWCNT). The electroanalytical performance of the prepared SPBE/MWCNT was intensively evaluated by measuring trace Hg(II) with square-wave anodic stripping voltammetry (SWASV). The results indicated that the SPBE modified with 2 wt% MWCNTs could offer a more sensitive response to trace Hg(II) than the bare SPBE. The stripping current obtained at SPBE/MWCNT was linear with Hg(II) concentration in the range from 0.2 to 40 µg/L (R(2) = 0.9976), with a detection limit of 0.09 µg/L (S/N = 3) under 180 s accumulation. The proposed "mercury-free" electrode, with extremely simple preparation and ultrahigh sensitivity, holds wide application prospects in both environmental and industrial monitoring. 2011 © The Japan Society for Analytical Chemistry

  19. Large-scale synthesis of bismuth sulfide nanorods by microwave irradiation

    International Nuclear Information System (INIS)

    Wu Jiliang; Qin Fan; Cheng Gang; Li Hui; Zhang Jiuhong; Xie Yaoping; Yang Haijian; Lu Zhong; Yu Xianglin; Chen Rong

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → Large-scale Bi 2 S 3 nanorods have been prepared by microwave irradiation methods. → CTAB and β-CD are beneficial to the formation of Bi 2 S 3 nanorods. → DMF, EG and DEG were favorable solvents. → Bismuth and sulfur precursors influenced the size and morphology. → A proposed formation mechanism of Bi 2 S 3 nanorods was summarized. - Abstract: Bismuth sulfide (Bi 2 S 3 ) has attracted considerable interest due to its potential applications in thermoelectric and electronic devices, optoelectronic devices, and biomedicine. In this study, large-scale highly crystalline Bi 2 S 3 nanorods were successfully prepared from bismuth citrate and thiourea (Tu) by microwave irradiation methods. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM, HRTEM) and selected area electron diffraction (SAED). The influences of reaction time, surfactants, solvents, and precursors on the formation of Bi 2 S 3 nanorods were discussed. The microwave irradiation method reduced reaction time by at least 80% in the synthesis of Bi 2 S 3 nanorods compared with the refluxing method. Cetyltrimethylammonium bromide (CTAB) and β-cyclodextrin (β-CD) were found to be beneficial to the formation of Bi 2 S 3 nanorods. N,N-dimethylformamide, ethylene glycol, and diethylene glycol were the favorable solvents in the fabrication of these nanorods. It was found that different bismuth and sulfur precursors influenced the sizes and morphologies of the Bi 2 S 3 nanorods. The proposed growth mechanism of Bi 2 S 3 nanorods was also discussed.

  20. Synthesis of Barium Titanate (BT) Nano Particles via Hydrothermal Route for the Production of BT-Polymer Nanocomposite

    Science.gov (United States)

    Habib, A.; Haubner, R.; Jakopic, G.; Stelzer, N.

    2007-08-01

    Barium titanate (high-k dielectric material) nano-powders (approx. 30 nm to 60 nm) were synthesised using hydrothermal route under moderate conditions. Effect of temperature and time was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction techniques. Obtained barium titanate nano-powders were dispersed in thermoplastic polymethyl methacrylate (PMMA) to get homogeneous dispersions. Thin layers were obtained using these dispersions to achieve BaTiO3 endorsed polymer layers by dip-coating for improved polymer insulators on various substrates e.g., glass, and Au sputtered silicon wafers. SEM and focused ion beam (FIB) techniques were used to study the dispersion of barium titanate nano-particles in PMMA. The layers obtained showed homogenous distribution of BaTiO3 nano particles with no agglomeration.

  1. Formation of aluminum titanate with small additions of MgO and SiO2

    International Nuclear Information System (INIS)

    Guedes-Silva, Cecilia Chaves; Ferreira, Thiago dos Santos; Genova, Luis Antonio; Carvalho, Flavio Machado de Souza

    2016-01-01

    The formation of aluminum titanate was investigated by isothermal treatments of samples obtained from equimolar mixtures of alumina and titania, containing small amounts of silica and magnesia. Results of differential thermal analysis and Rietveld refinements of data collected by X-ray powder diffraction (XRPD) showed that additions of silica in amounts used in this work did not influence the formation of aluminum titanate. However, the presence of magnesia favored the formation of aluminum titanate in two steps, first one by incorporating Mg 2+ into Al 2 TiO 5 lattice during its initial formation, and the second one by accelerating the Al 2 TiO 5 formation, contributing to large quantities of this phase. MgO doped samples have also developed a more suitable microstructure for stabilizing of Al 2 TiO 5 , what make them promising for applications such as thermal barriers, internal combustion engines and support material for catalyst. (author)

  2. Diurnal variations of Titan's ionosphere

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

    2009-06-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

  3. Calorimetric measurements on hafnium titanate

    International Nuclear Information System (INIS)

    Kandan, R.; Prabhakara Reddy, B.; Panneerselvam, G.; Nagarajan, K.

    2012-01-01

    Owing to its desirable nuclear and mechanical properties such as good absorption cross-section for thermal neutrons (105 barns), hafnium titanate (HfTiO 4 ) finds application as control rods for nuclear reactors. An accurate knowledge of the thermo physical properties of this material is necessary for design of control rod and for modeling its performance. Heat capacity is an important thermodynamic property that determines the temperature dependent variation of all other thermodynamic properties. Hence enthalpy increments of hafnium titanate (HfTiO 4 ) were measured in the temperature range 803-1663 K by employing the method of inverse drop calorimetry using high temperature differential calorimeter

  4. Preparation and characterization of bismuth ruthenate pyrochlore via solid state reaction and sol-gel methods

    Directory of Open Access Journals (Sweden)

    Mayuree Sansernnivet

    2010-01-01

    Full Text Available Bismuth ruthenate pyrochlores, potential cathode materials for intermediate temperature solid oxide fuel cells(ITSOFCs, were prepared via solid-state and sol-gel method. Effects of the preparation routes and conditions on the phase and microstructures of the materials were investigated in this study using XRD and SEM. The study showed that the preparation method and the adding sequence of the starting meterials have a significant effect on the crystal phase and the particle size obtained. Sol-gel synthesis could yield a material with only pyrochlore structure, i.e. Bi2Ru2O7, while the solid state method yielded powder with a small amount of the secondary RuO2 phase. The sol-gel synthesis resulted in materialswith a finer particle size (~0.3-1.0 μm compared to powder synthesized via the solid state reaction method.

  5. Titan's hydrodynamically escaping atmosphere

    Science.gov (United States)

    Strobel, Darrell F.

    2008-02-01

    The upper atmosphere of Titan is currently losing mass at a rate ˜(4-5)×10 amus, by hydrodynamic escape as a high density, slow outward expansion driven principally by solar UV heating by CH 4 absorption. The hydrodynamic mass loss is essentially CH 4 and H 2 escape. Their combined escape rates are restricted by power limitations from attaining their limiting rates (and limiting fluxes). Hence they must exhibit gravitational diffusive separation in the upper atmosphere with increasing mixing ratios to eventually become major constituents in the exosphere. A theoretical model with solar EUV heating by N 2 absorption balanced by HCN rotational line cooling in the upper thermosphere yields densities and temperatures consistent with the Huygens Atmospheric Science Investigation (HASI) data [Fulchignoni, M., and 42 colleagues, 2005. Nature 438, 785-791], with a peak temperature of ˜185-190 K between 3500-3550 km. This model implies hydrodynamic escape rates of ˜2×10 CHs and 5×10 Hs, or some other combination with a higher H 2 escape flux, much closer to its limiting value, at the expense of a slightly lower CH 4 escape rate. Nonthermal escape processes are not required to account for the loss rates of CH 4 and H 2, inferred by the Cassini Ion Neutral Mass Spectrometer (INMS) measurements [Yelle, R.V., Borggren, N., de la Haye, V., Kasprzak, W.T., Niemann, H.B., Müller-Wodarg, I., Waite Jr., J.H., 2006. Icarus 182, 567-576].

  6. Interaction of Titan's atmosphere with Saturn's magnetosphere

    International Nuclear Information System (INIS)

    Hartle, R.E.

    1985-01-01

    The Voyager 1 measurements made during the Titan flyby reveal that Saturn's rotating magnetospheric plasma interacts directly with Titan's neutral atmosphere and ionosphere. This results from the lack of an intrinsic magnetic field at Titan. The interaction induces a magnetosphere which deflects the flowing plasma around Titan and forms a plasma wake downstream. Within the tail of the induced magnetosphere, ions of ionospheric origin flow away from Titan. Just outside Titan's magnetosphere, a substantial ion-exosphere forms from an extensive hydrogen-nitrogen exosphere. The exospheric ions are picked up and carried downstream into the wake by the plasma flowing around Titan. Mass loading produced by the addition of exospheric ions slows the wake plasma down considerably in the vicinity of the magnetopause. 36 references

  7. Bismuth( Ⅲ ) Salts: Green Catalysts for Organic Transformations

    Institute of Scientific and Technical Information of China (English)

    C. Le Roux

    2005-01-01

    @@ 1Introduction Bismuth, the heaviest stable element in the periodic table, stands out from other heavy elements (such as mercury, thallium and lead) due to its relatively non-toxic character which confers on bismuth the enviable status of being an eco-friendly element. Therefore, bismuth and its compounds hold considerable promise as useful catalysts for green chemistry. The research presented in this communication is devoted to the applications of bismuth( Ⅲ ) salts as catalysts for organic transformations.After some general comments about bismuth and a short presentation of the various applications of bismuth( Ⅲ ) salts in organic synthesis, this communication will focus on the works done in our research group during the last several years which deals mainly with electrophilic substitutions. When appropriate, some mechanistic details will be given.

  8. Thermal decomposition synthesis of nanorods bismuth sulphide from bismuth N-ethyl cyclohexyl dithiocarbamate complex

    International Nuclear Information System (INIS)

    Abdullah, Nurul Hidayah; Zainal, Zulkarnain; Silong, Sidik; Tahir, Mohamed Ibrahim Mohamed; Tan, Kar-Ban; Chang, Sook-Keng

    2016-01-01

    Highlights: • Bismuth N-ethyl cyclohexyl dithiocarbamate was used as single source precursor. • No surfactant was used in the preparation of Bi_2S_3 nanorods. • Pure phase orthorhombic Bi_2S_3 is obtained. • Bismuth sulphide with an average atomic ratio of Bi:S close to 2:3 is obtained. - Abstract: Nanorods of bismuth sulphide were prepared by thermal decomposition of bismuth N-ethyl cyclohexyl dithiocarbamate at different calcination duration. X-ray diffraction (XRD) analysis shows that at 400 °C, the precursor was fully decomposed to orthorhombic bismuth sulphide after 2 h of calcination. Besides, calcination duration does not affect the existence of Bi_2S_3 phase. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses reveal that Bi_2S_3 nanorods with an average width ranging from 29–36 nm were obtained. Energy dispersive X-ray (EDX) analysis confirmed the atomic ratio of Bi and S close to 2:3, giving a possible composition of Bi_2S_3. Direct band gap energy of Bi_2S_3 decreases from 1.83 eV to 1.54 eV as calcination time increases.

  9. On the use of bismuth as a neutron filter

    CERN Document Server

    Adib, M

    2003-01-01

    A formula is given which, for neutron energies in the range 10 sup - sup 4 bismuth temperature and crystalline form. Computer programs have been developed which allow calculations for the Bi rhombohedral structure in its poly-crystalline form and its equivalent hexagonal close-packed structure. The calculated total neutron cross-sections for poly-crystalline Bi at different temperatures were compared with the measured values. An overall agreement is indicated between the formula fits and experimental data. Agreement was also obtained for values of Bi-single crystals, at room and liquid nitrogen temperatures. A feasibility study for use of Bi in powdered form, as a cold neutron filter, is detailed in terms of the optimum Bi-single crystal thickness, mosaic spread, temperature and cutting plane for efficient transmission of thermal-reactor neutrons, and also for rejection of the accom...

  10. On the use of bismuth as a neutron filter

    Science.gov (United States)

    Adib, M.; Kilany, M.

    2003-02-01

    A formula is given which, for neutron energies in the range 10 -4< E<10 eV, permits calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of bismuth temperature and crystalline form. Computer programs have been developed which allow calculations for the Bi rhombohedral structure in its poly-crystalline form and its equivalent hexagonal close-packed structure. The calculated total neutron cross-sections for poly-crystalline Bi at different temperatures were compared with the measured values. An overall agreement is indicated between the formula fits and experimental data. Agreement was also obtained for values of Bi-single crystals, at room and liquid nitrogen temperatures. A feasibility study for use of Bi in powdered form, as a cold neutron filter, is detailed in terms of the optimum Bi-single crystal thickness, mosaic spread, temperature and cutting plane for efficient transmission of thermal-reactor neutrons, and also for rejection of the accompanying fast neutrons and gamma rays.

  11. On the use of bismuth as a neutron filter

    Energy Technology Data Exchange (ETDEWEB)

    Adib, M.; Kilany, M. E-mail: kilany11@hotmail.com

    2003-02-01

    A formula is given which, for neutron energies in the range 10{sup -4}bismuth temperature and crystalline form. Computer programs have been developed which allow calculations for the Bi rhombohedral structure in its poly-crystalline form and its equivalent hexagonal close-packed structure. The calculated total neutron cross-sections for poly-crystalline Bi at different temperatures were compared with the measured values. An overall agreement is indicated between the formula fits and experimental data. Agreement was also obtained for values of Bi-single crystals, at room and liquid nitrogen temperatures. A feasibility study for use of Bi in powdered form, as a cold neutron filter, is detailed in terms of the optimum Bi-single crystal thickness, mosaic spread, temperature and cutting plane for efficient transmission of thermal-reactor neutrons, and also for rejection of the accompanying fast neutrons and gamma rays.

  12. On the use of bismuth as a neutron filter

    International Nuclear Information System (INIS)

    Adib, M.; Kilany, M.

    2003-01-01

    A formula is given which, for neutron energies in the range 10 -4 < E<10 eV, permits calculation of the nuclear capture, thermal diffuse and Bragg scattering cross-sections as a function of bismuth temperature and crystalline form. Computer programs have been developed which allow calculations for the Bi rhombohedral structure in its poly-crystalline form and its equivalent hexagonal close-packed structure. The calculated total neutron cross-sections for poly-crystalline Bi at different temperatures were compared with the measured values. An overall agreement is indicated between the formula fits and experimental data. Agreement was also obtained for values of Bi-single crystals, at room and liquid nitrogen temperatures. A feasibility study for use of Bi in powdered form, as a cold neutron filter, is detailed in terms of the optimum Bi-single crystal thickness, mosaic spread, temperature and cutting plane for efficient transmission of thermal-reactor neutrons, and also for rejection of the accompanying fast neutrons and gamma rays

  13. Structure, spectra and stability of solid bismuth carbonates

    International Nuclear Information System (INIS)

    Taylor, Peter; Sunder, S.; Lopata, V.J.

    1984-01-01

    A previously unreported basic bismuth carbonate, (BiO)sub(4)(OH)sub(2)COsub(3), has been identified as an intermediate product in the interconversion of α-Bisub(2)Osub(3) and synthetic bismutite, (BiO)sub(2)COsub(3), in aqueous carbonate solutions. It has a narrow stability field between COsub(2) partial pressures of 10sup(-5.5+-1.0) Pa, in the presence of dilute aqueous solution at 25 degrees C. Gibbs energies of formation, calculated from these partial pressures, are Δsub(f)Gsup(0)((BiO)sub(4)(OH)sub(2)COsub(3),s,298.15 K)-1678 +- 9 kJ molsup(-1) and Δsub(f)Gsup(0)((BiO)sub(2)COsub(3),s,298.15 K)=-945 +- 7 kJ molsup(-1). The two carbonates have been compared by thermogravimetric analysis, X-ray powder diffractometry, and infrared and Raman spectroscopy. The unit cell of (BiO)sub(4)(OH)sub(2)COsub(3) is dimensionally orthorhombic, with a=10.772(1), b=5.4898(5), c=14.757(1)angstrom,Z=4, but its true symmetry is probably triclinic. A structural model for (BiO)sub(4)(OH)sub(2)COsub(3), and two modified models for (BiO)sub(2)COsub(3), are proposed. The possible natural occurrence of (BiO)sub(4)(OH)sub(2)COsub(3) is discussed

  14. Barium titanate coated with magnesium titanate via fused salt method and its dielectric property

    International Nuclear Information System (INIS)

    Chen Renzheng; Cui Aili; Wang Xiaohui; Li Longtu

    2003-01-01

    Barium titanate fine particles were coated homogeneously with magnesium titanate via the fused salt method. The thickness of the magnesium titanate film is 20 nm, as verified by TEM and XRD. The mechanism of the coating is that: when magnesium chloride is liquated in 800 deg. C, magnesium will replace barium in barium titanate, and form magnesium titanate film on the surface of barium titanate particles. Ceramics sintered from the coated particles show improved high frequency ability. The dielectric constant is about 130 at the frequency from 1 to 800 MHz

  15. Comparison of lanthanum substituted bismuth titanate (BLT) thin films deposited by sputtering and pulsed laser deposition

    International Nuclear Information System (INIS)

    Besland, M.P.; Djani-ait Aissa, H.; Barroy, P.R.J.; Lafane, S.; Tessier, P.Y.; Angleraud, B.; Richard-Plouet, M.; Brohan, L.; Djouadi, M.A.

    2006-01-01

    Bi 4-x La x Ti 3 O 12 (BLT x ) (x = 0 to 1) thin films were grown on silicon (100) and platinized substrates Pt/TiO 2 /SiO 2 /Si using RF diode sputtering, magnetron sputtering and pulsed laser deposition (PLD). Stoichiometric home-synthesized targets were used. Reactive sputtering was investigated in argon/oxygen gas mixture, with a pressure ranging from 0.33 to 10 Pa without heating the substrate. PLD was investigated in pure oxygen, at a chamber pressure of 20 Pa for a substrate temperature of 400-440 deg. C. Comparative structural, chemical, optical and morphological characterizations of BLT thin films have been performed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Photoelectron Spectroscopy (XPS), Spectro-ellipsometric measurements (SE) and Atomic Force Microscopy (AFM). Both sputtering techniques allow to obtain uniform films with thickness ranging from 200 to 1000 nm and chemical composition varying from (Bi,La) 2 Ti 3 O 12 to (Bi,La) 4.5 Ti 3 O 12 , depending on deposition pressure and RF power. In addition, BLT films deposited by magnetron sputtering, at a pressure deposition ranging from 1.1 to 5 Pa, were well-crystallized after a post-deposition annealing at 650 deg. C in oxygen. They exhibit a refractive index and optical band gap of 2.7 and 3.15 eV, respectively. Regarding PLD, single phase and well-crystallized, 100-200 nm thick BLT films with a stoichiometric (Bi,La) 4 Ti 3 O 12 chemical composition were obtained, exhibiting in addition a preferential orientation along (200). It is worth noting that BLT films deposited by magnetron sputtering are as well-crystallized than PLD ones

  16. Structural and dielectric properties of Gd doped bismuth ferrite-lead titanate

    International Nuclear Information System (INIS)

    Mohanty, N. K.; Behera, A. K.; Satpathy, S. K.; Behera, B.; Nayak, P.

    2014-01-01

    0.5BiGd x Fe 1−x O 3 −0.5PbTiO 3 with x=0.05, 0.10, 0.15, 0.20 composite was prepared by mixed oxide method. Structural characterization was performed by X-ray diffraction and studied that the materials show tetragonal structure at room temperature for all concentration of Gd. Studies of dielectric properties (ε r and tanδ) of the above compound at different frequencies in a wide range of temperature (25°-500°C) with an impedance analyser revealed that the dielectric constant increases with increase in Gd concentration as well temperature and the compound do not have any dielectric anomaly in the studied frequency and temperature range

  17. B-site substituted solid solutions on the base of sodium-bismuth titanate

    Directory of Open Access Journals (Sweden)

    V. M. Ishchuk

    2016-12-01

    Full Text Available The paper presents results of studies of the formation of phases during the solid-state synthesis in the [(Na0.5Bi0.50.80Ba0.20](Ti1–yByO3 system of solid solutions with B-site substitutions. The substitutions by zirconium, tin and ion complexes (In0.5Nb0.5 and (Fe0.5Nb0.5 have been studied. It has been found that the synthesis is a multi-step process associated with the formation of a number of intermediate phases (depending on the compositions and calcination temperatures. Single-phase solid solutions have been produced at the calcination temperatures in the interval 1000–1100∘C. An increase in the substituting ions concentration leads to a linear increase of the crystal cell size. At the same time, the tolerance factor gets reduced boosting the stability of the antiferroelectric phase as compared to that of the ferroelectric phase.

  18. Hubble Observes Surface of Titan

    Science.gov (United States)

    1994-01-01

    Scientists for the first time have made images of the surface of Saturn's giant, haze-shrouded moon, Titan. They mapped light and dark features over the surface of the satellite during nearly a complete 16-day rotation. One prominent bright area they discovered is a surface feature 2,500 miles across, about the size of the continent of Australia.Titan, larger than Mercury and slightly smaller than Mars, is the only body in the solar system, other than Earth, that may have oceans and rainfall on its surface, albeit oceans and rain of ethane-methane rather than water. Scientists suspect that Titan's present environment -- although colder than minus 289 degrees Fahrenheit, so cold that water ice would be as hard as granite -- might be similar to that on Earth billions of years ago, before life began pumping oxygen into the atmosphere.Peter H. Smith of the University of Arizona Lunar and Planetary Laboratory and his team took the images with the Hubble Space Telescope during 14 observing runs between Oct. 4 - 18. Smith announced the team's first results last week at the 26th annual meeting of the American Astronomical Society Division for Planetary Sciences in Bethesda, Md. Co-investigators on the team are Mark Lemmon, a doctoral candidate with the UA Lunar and Planetary Laboratory; John Caldwell of York University, Canada; Larry Sromovsky of the University of Wisconsin; and Michael Allison of the Goddard Institute for Space Studies, New York City.Titan's atmosphere, about four times as dense as Earth's atmosphere, is primarily nitrogen laced with such poisonous substances as methane and ethane. This thick, orange, hydrocarbon haze was impenetrable to cameras aboard the Pioneer and Voyager spacecraft that flew by the Saturn system in the late 1970s and early 1980s. The haze is formed as methane in the atmosphere is destroyed by sunlight. The hydrocarbons produced by this methane destruction form a smog similar to that found over large cities, but is much thicker

  19. Organic chemistry in Titan's atmosphere

    Science.gov (United States)

    Scattergood, T.

    1982-01-01

    Laboratory photochemical simulations and other types of chemical simulations are discussed. The chemistry of methane, which is the major known constituent of Titan's atmosphere was examined with stress on what can be learned from photochemistry and particle irradiation. The composition of dust that comprises the haze layer was determined. Isotope fractionation in planetary atmospheres is also discussed.

  20. Chemical compatibility study of lithium titanate with Indian reduced activation ferritic martensitic steel

    International Nuclear Information System (INIS)

    Sonak, Sagar; Jain, Uttam; Haldar, Rumu; Kumar, Sanjay

    2015-01-01

    Highlights: • Chemical compatibility between Li_2TiO_3 and Indian RAFM steel has been studied at ITER operating temperature. • The lithium titanate chemically reacted with ferritic martensitic steel to form a brittle and non-adherent oxide layer. • The layer grew in a parabolic manner as a function of heating time. • Diffusion of oxygen (from Li_2TiO_3) appears to be controlling the oxide layer. - Abstract: Chemical compatibility between lithium titanate and Indian reduced activation ferritic-martensitic steel (In-RAFMS) was studied for the first time under ITER operating temperature. Lithium titanate required for the study was synthesized in-house. Coupons of In-RAFMS were packed inside lithium titanate powder and heated at 550 °C up to 900 h under inert argon atmosphere. The lithium titanate chemically reacted with ferritic martensitic steel to form a brittle and non-adherent oxide layer. The layer grew in a parabolic manner as a function of heating time. Microstructural and phase evolution of this oxide layer was studied using XRD, SEM and EPMA. Iron and chromium enriched zones were found within the oxide layer. Diffusion of oxygen (from Li_2TiO_3) appears to be controlling the oxide layer.

  1. "Chemical contraction" in rubidium-bismuth melts

    Science.gov (United States)

    Khairulin, R. A.; Abdullaev, R. N.; Stankus, S. V.

    2017-10-01

    The density and thermal expansion of liquid rubidium and rubidium-bismuth alloy containing 25.0 at % Bi were measured by the gamma-ray attenuation technique at temperatures from liquidus to 1000 K. The results of this study were compared with the data obtained by other authors. The molar volume of the Rb75Bi25 melt strongly deviates from the additivity rule for ideal solutions.

  2. Electrocatalytic activity of bismuth doped silver electrodes

    CERN Document Server

    Amjad, M

    2002-01-01

    Investigation of redox reactions on silver, and bismuth doped silver electrodes in aqueous KOH solutions, by using potentiostatic steady-state polarization technique, has been carried out. The redox wave potential and current displacements along with multiplicity of the latter have been examined. These electrodes were employed for the oxidation of organic molecules such as ethylamine in alkaline media. Subsequently, these electrodes were ranked with respect to their activity for the redox reactions. (author)

  3. Powder technology

    International Nuclear Information System (INIS)

    Agueda, Horacio

    1989-01-01

    Powder technology is experiencing nowadays a great development and has broad application in different fields: nuclear energy, medicine, new energy sources, industrial and home artifacts, etc. Ceramic materials are of daily use as tableware and also in the building industry (bricks, tiles, etc.). However, in machine construction its utilization is not so common. The same happens with metals: powder metallurgy is employed less than traditional metal forming techniques. Both cases deal with powder technology and the forming techniques as far as the final consolidation through sintering processes are very similar. There are many different methods and techniques in the forming stage: cold-pressing, slip casting, injection molding, extrusion molding, isostatic pressing, hot-pressing (which involves also the final consolidation step), etc. This variety allows to obtain almost any desired form no matter how complex it could be. Some applications are very specific as in the case of UO 2 pellets (used as nuclear fuels) but with the same technique and other materials, it is possible to manufacture a great number of different products. This work shows the characteristics and behaviour of two magnetic ceramic materials (ferrites) fabricated in the laboratory of the Applied Research Division of the Bariloche Atomic Center for different purposes. Other materials and products made with the same method are also mentioned. Likewise, densities and shrinkage obtained by different methods of forming (cold-pressing, injection molding, slip casting and extrusion molding) using high-purity alumina (99.5% Al 2 O 3 ). Finally, different applications of such methods are given. (Author) [es

  4. Doping of germanium telluride with bismuth tellurides

    International Nuclear Information System (INIS)

    Abrikosov, N.Kh.; Karpinskij, O.G.; Makalatiya, T.Sh.; Shelimova, L.E.

    1981-01-01

    Effect of germanium telluride doping with bismuth fellurides (Bi 2 Te 3 ; BiTe; Bi 2 Te) on phase transition temperature, lattice parameters and electrophysical properties of alloys is studied. It is shown that in alloys of GeTe-Bi 2 Te 3 (BiTe)(Bi 2 Te) cross sections solid solution of GeTe with Bi 2 Te 3 , characterized by deviation from stoichiometry, and germanium in the second phase the quantity of which increases during the transition from GeTe-Bi 2 Te 3 cross section to GeTe-Bi 2 Te are in equilibrium. Lower values of holes concentration and of electric conductivity and higher values of thermo e.m.f. coefficient in comparison with alloys of GeTe-Bi 2 Te 3 cross section with the same bismuth content are characterized for GeTe-Bi 2 Te cross section alloys. It is shown that in the range of GeTe-base solid solution the α→γ phase transformation which runs trough the two-phase region (α→γ) is observed with tellurium content increase. Extension of α-phase existence region widens with the bismuth content increase. Peculiarities of interatomic interaction in GeTe-base solid solutions with isovalent and heterovalent cation substitution are considered [ru

  5. Substutited molybdates of bismuth on a basis of Bi13Mo5O34±δ: production and properties

    Directory of Open Access Journals (Sweden)

    Z. A. Mikhailovskaya

    2014-11-01

    Full Text Available The present work is devoted to the investigation of the methods of a synthesis and properties of the one of the most interesting one-dimensional oxygen –ion conductors, the Bi13Mo5O34±δ –based complex oxides. The general compositions of these bismuth molybdates are Bi13Mo5-хMeхO34-δ, and Bi13-yMeyMo5O34-δ, with Me = Mg, Ca, Sr, Ba (IIA group and Co, Fe, Ni (Fe triade. The samples have been synthesized using conventional ceramic technology. The powders and pellets of the bismuth molybdates were studied by X-Ray diffraction, scanning electron microscopy, laser dispersion, dilatometry, atom absorption and inductively-coupled plasma atomic emission spectrometry. Electrical conductivity has been studied using impedance spectroscopy method.

  6. Effect of excess bismuth on the dielectric and piezoelectric properties of strontium bismuth niobate ceramics

    International Nuclear Information System (INIS)

    Verma, Maya; Tanwar, Amit; Sreenivas, K.

    2013-01-01

    Excess Bismuth Strontium Bismuth Niobate (Sr 2 Bi 2 Nb 2 O 9 + x wt% Bi 2 O 3 ) ceramics were prepared using conventional solid state reaction method by varying x in the range (x=0%wt - 20%wt). X-ray diffraction studies reveal no significant shift in the peak positions as the Bi content increases from 0.0 to 5%wt. However, at a higher content of Bi beyond x = 5wt% secondary phases relating to Bi 2 O 3 are identified. The c-axis orientation is found to be minimum for SBN ceramic prepared with 5% excess bismuth whereas with further increase in excess Bi 2 O 3 addition during processing, SBN ceramics show a much stronger c-axis orientation. Room temperature dielectric constant measured at 100 KHz is found to increase from 117 to 130 with increase in Bi content from x = 0 to 10wt% suggesting Bi addition has make up for the bismuth losses at higher sintering temperature (1200℃), however with further increase in Bi content (x > 10wt%), the dielectric constant decreases, and could be due to the increased probability of segregation of Bi on the grains of SBN ceramics. The improvement in ferroelectric properties were obtained when the bismuth excess is increased from 0% to 5%. It may be observed that on increasing the excess bismuth to 5%, the transition temperature increases from 424 to 450℃, while further increasing to 10%, transition becomes slightly diffused and phase transition temperature gets decreased to 398℃, which may be due to the formation of secondary phase. 5% excess Bi is found to enhance the dielectric and ferroelectricity properties, and any further increase of Bi in excess (>10%) during processing is found to degrade the electrical and functional properties of SBN. (author)

  7. Amino acidis derived from Titan tholins

    Science.gov (United States)

    Khare, Bishun N.; Sagan, Carl; Ogino, Hiroshi; Nagy, Bartholomew; Er, Cevat

    1986-01-01

    The production of amino acids by acid treatment of Titan tholin is experimentally investigated. The synthesis of Titan tholin and the derivatization of amino acids to N-trifluoroacetyl isopropyl esters are described. The gas chromatography/mass spectroscopy analysis of the Titan tholins reveals the presence of glycine, alpha and beta alainine, and aspartic acid, and the total yield of amino acids is about 0.01.

  8. Effectiveness of ranitidine bismuth citrate and proton pump inhibitor ...

    African Journals Online (AJOL)

    Effectiveness of ranitidine bismuth citrate and proton pump inhibitor based triple therapies of Helicobacter pylori in Turkey. ... Results: When we look at the eradication rates of the treatment groups, only two groups (ranitidine bismuth citrate and rabeprazole groups) had eradication rates greater than 80%, both at intention to ...

  9. Bismuth-silver mineralization in the Sergozerskoe gold occurrence

    Directory of Open Access Journals (Sweden)

    Kalinin A. A.

    2017-03-01

    Full Text Available Bismuth-silver mineralization attendant to gold mineralization in the Sergozerskoe gold occurrence has been studied in detail. Bi-Ag mineralization is connected with diorite porphyry dykes, which cut volcanic-sedimentary Lopian complexes of the Strel'ninsky greenstone belt – hornblendite and actinolite-chlorite amphibolites, biotite and bi-micaceous gneisses. Distribution of Bi-Ag mineralization similar to gold mineralization is controlled by 80 m thick zone of silicification. Bi minerals are found in brecciated diorite porphyry. Bismuth-silver mineralization includes native metals (bismuth, electrum, silver, tellurides (hedleyite, hessite, selenides (ikunolite, sulfides and sulfosalts of Bi and Ag (matildite, lillianite, eckerite, jalpaite, prustite, acanthite, a few undiagnosed minerals. All Bi and Ag minerals associate with galena. Composition of mineralization evolved from early to late stages of development, depending on intensity of rock alteration. The earliest Bi-Ag minerals were native bismuth and hedleyite formed dissemination in galena, and electrum with 30-45 mass.% Au. Later native bismuth was partly substituted by silver and bismuth sulfosalts and bismuth sulfides. The latest minerals were low-temperature silver sulfides eckerite, jalpaite, and acanthite, which were noted only in the most intensively altered rocks. As soon as the process of formation of Bi-Ag mineralization is the same as formation of gold, findings of bismuth-silver mineralization can serve as a positive exploration sign for gold in the region.

  10. Bismuth-doped La1.75Sr0.25NiO4+: δ as a novel cathode material for solid oxide fuel cells

    NARCIS (Netherlands)

    Zhu, Zhesheng; Li, Mei; Xia, Changrong; Bouwmeester, Henny J.M.

    2017-01-01

    Bismuth has been doped into mixed ionic-electronic conducting La1.75Sr0.25NiO4+δ (LSN) with the 2D K2NiF4-type structure to evaluate its influence on various properties of the host material, which include its potential use as a SOFC cathode. X-ray powder diffraction indicates that LSN retains its

  11. Application of titanates, niobates, and tantalates to neutralized defense waste decontamination: materials properties, physical forms, and regeneration techniques. Final report

    International Nuclear Information System (INIS)

    Dosch, R.G.

    1981-01-01

    A study of the application of sodium titanate (ST) to the decontamination of neutralized defense waste has been completed. The work was directed at Sr removal from dissolved salt cake, simulated in this work with a 6.0 N NaNO 3 - 0.6 N NaOH solution. Three physical forms of the titanates were developed including powder, pellets, and titanate-loaded resin beads and all were found to be superior to conventional organic ion exchange in this application. When spent, the titanate materials can be calcined to an oxide from which is a stable waste form in itself or can be added directly to a glass melter to become part of a vitrified waste form. Radiation stability of titanate powder and resin forms was assessed in tests in which these materials were exposed to 60 Co radiation. The strontium exchange capacity of the powder remained constant through a dose of 3 x 10 7 rads and retained 50% capacity after a dose of 2 x 10 9 rads. The primary mechanism involved in loss of capacity was believed to be heating associated with the irradiation. The resin forms were unchanged through a dose of 5 x 10 8 rads and retained 30% capacity after a dose of 2 x 10 9 rads. The latter dose resulted in visible degradation of the resin matrix. Anion exchange resins loaded with sodium niobate and sodium tantalate were also prepared by similar methods and evaluated for this application. These materials had Sr sorption properties comparable to the titanate material; however, they would have to provide a significant improvement to justify their higher cost

  12. Heat capacity, enthalpy and entropy of bismuth niobate and bismuth tantalate

    Czech Academy of Sciences Publication Activity Database

    Hampl, M.; Strejc, A.; Sedmidubský, D.; Růžička, K.; Hejtmánek, Jiří; Leitner, J.

    2006-01-01

    Roč. 179, - (2006), s. 77-80 ISSN 0022-4596 Institutional research plan: CEZ:AV0Z10100521 Keywords : heat capacity * heat of formation * heat content * bismuth perovskite Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.107, year: 2006

  13. Heat-Pipe Bismuth Laser; Examination of Laser Action at 4722A in Bismuth Vapor

    Science.gov (United States)

    1976-11-01

    11, 15(1975). of Type 6p 3 -6p 2 7s in the Bismuth Atomic Spectrum in Intermediate Coupling," Acta Physica Polonica A47, 231(1975). 19. A.N. Nesmeyanov...Calculated Transit n Probabilities and Lifetimes for the First Excited Configuration np (n+l)s in the Neutral As, Sb and Bi Atoms, " Physica Scripta

  14. Powder of a copper oxide superconductor precursor, fabrication process and use for the preparation of superconducting oxide

    International Nuclear Information System (INIS)

    Dehaudt, P.

    1990-01-01

    The precursor powder comprises at least a copper compound (hydroxide, oxide and hydroxynitrates), at least a rare earth and/or yttrium compound (nitrates, hydroxides and hydroxynitrates) or bismuth oxide and at least an alkaline earth nitrate. It can be prepared by atomization drying of a suspension a copper precipitate or coprecipitate and other elements of the superconducting oxide in solution [fr

  15. Titan Montgolfiere Buoyancy Modulation System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Titan is ideally suited for balloon exploration due to its low gravity and dense atmosphere. Current NASA mission architectures baseline Montgolfiere balloon...

  16. Bismuth X-ray absorber studies for TES microcalorimeters

    International Nuclear Information System (INIS)

    Sadleir, J.E.; Bandler, S.R.; Brekosky, R.P.; Chervenak, J.; Figueroa-Feliciano, E.; Finkbeiner, F.; Iyomoto, N.; Kelley, R.L.; Kilbourne, C.A.; King, J.M.; Porter, F.S.; Robinson, I.K.; Saab, T.; Talley, D.J.

    2006-01-01

    Bismuth's large atomic number and low carrier density makes it an attractive X-ray absorber material for microcalorimeters. Bismuth's long Fermi wavelength and long mean free paths have motivated much interest in the fabrication of high quality bismuth films to study quantum size effects. Despite such incentives, fabrication of high quality bismuth films has proven difficult, and measured properties of such films are highly variable in the literature. Implementing a bismuth deposition process for TES (superconducting Transition Edge Sensor) device fabrication presents additional challenges particularly at interfaces due to the inherent granularity and surface roughness of its films, its low melting point, and its tendency to diffuse and form undesired intermetallic phases. We report observations of Bi-Cu and Bi-Au diffusion in our devices correlating with large shifts in T c (superconducting transition temperature). Using SEM and in situ R vs T annealing experiments we have been able to study these diffusion processes and identify their activation temperatures

  17. Titan's geoid and hydrology: implications for Titan's geological evolution

    Science.gov (United States)

    Sotin, Christophe; Seignovert, Benoit; Lawrence, Kenneth; MacKenzie, Shannon; Barnes, Jason; Brown, Robert

    2014-05-01

    A 1x1 degree altitude map of Titan is constructed from the degree 4 gravity potential [1] and Titan's shape [2] determined by the Radio Science measurements and RADAR observations of the Cassini mission. The amplitude of the latitudinal altitude variations is equal to 300 m compared to 600 m for the amplitude of the latitudinal shape variations. The two polar caps form marked depressions with an abrupt change in topography at exactly 60 degrees at both caps. Three models are envisaged to explain the low altitude of the polar caps: (i) thinner ice crust due to higher heat flux at the poles, (ii) fossil shape acquired if Titan had higher spin rate in the past, and (iii) subsidence of the crust following the formation of a denser layer of clathrates as ethane rain reacts with the H2O ice crust [3]. The later model is favored because of the strong correlation between the location of the cloud system during the winter season and the latitude of the abrupt change in altitude. Low altitude polar caps would be the place where liquids would run to and eventually form large seas. Indeed, the large seas of Titan are found at the deepest locations at the North Pole. However, the lakes and terrains considered to be evaporite candidates due to their spectral characteristics in the infrared [4,5] seem to be perched. Lakes may have been filled during Titan's winter and then slowly evaporated leaving material on the surface. Interestingly, the largest evaporite deposits are located at the equator in a deep depression 150 m below the altitude of the northern seas. This observation seems to rule out the presence of a global subsurface hydrocarbon reservoir unless the evaporation rate at the equator is faster than the transport of fluids from the North Pole to the equator. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Iess L. et al. (2012) Science, doi 10.1126/science.1219631. [2] Lorenz R.D. (2013

  18. Titan from Cassini-Huygens

    CERN Document Server

    Brown, Robert H; Waite, J. Hunter

    2010-01-01

    This book reviews our current knowledge of Saturn's largest moon Titan featuring the latest results obtained by the Cassini-Huygens mission. A global author team addresses Titan’s origin and evolution, internal structure, surface geology, the atmosphere and ionosphere as well as magnetospheric interactions. The book closes with an outlook beyond the Cassini-Huygens mission. Colorfully illustrated, this book will serve as a reference to researchers as well as an introduction for students.

  19. Thermal stability of titanate nanotubes

    Czech Academy of Sciences Publication Activity Database

    Králová, Daniela; Kužel, R.; Kovářová, Jana; Dybal, Jiří; Šlouf, Miroslav

    2009-01-01

    Roč. 16, 2a (2009), s. 41-43 ISSN 1211-5894. [Struktura - Colloquium of Czech and Slovak Crystallographic Association. Hluboká nad Vltavou, 22.06.2009-25.06.2009] R&D Projects: GA ČR GA203/07/0717; GA AV ČR KAN200520704 Institutional research plan: CEZ:AV0Z40500505 Keywords : titanate nanotubes * thermal stability Subject RIV: CD - Macromolecular Chemistry

  20. Anion and cation diffusion in barium titanate and strontium titanate

    International Nuclear Information System (INIS)

    Kessel, Markus Franz

    2012-01-01

    Perovskite oxides show various interesting properties providing several technical applications. In many cases the defect chemistry is the key to understand and influence the material's properties. In this work the defect chemistry of barium titanate and strontium titanate is analysed by anion and cation diffusion experiments and subsequent time-of-flight secondary ion mass spectrometry (ToF-SIMS). The reoxidation equation for barium titanate used in multi-layer ceramic capacitors (MLCCs) is found out by a combination of different isotope exchange experiments and the analysis of the resulting tracer diffusion profiles. It is shown that the incorporation of oxygen from water vapour is faster by orders of magnitude than from molecular oxygen. Chemical analysis shows the samples contain various dopants leading to a complex defect chemistry. Dysprosium is the most important dopant, acting partially as a donor and partially as an acceptor in this effectively acceptor-doped material. TEM and EELS analysis show the inhomogeneous distribution of Dy in a core-shell microstructure. The oxygen partial pressure and temperature dependence of the oxygen tracer diffusion coefficients is analysed and explained by the complex defect chemistry of Dy-doped barium titanate. Additional fast diffusion profiles are attributed to fast diffusion along grain boundaries. In addition to the barium titanate ceramics from an important technical application, oxygen diffusion in cubic, nominally undoped BaTiO 3 single crystals has been studied by means of 18 O 2 / 16 O 2 isotope exchange annealing and subsequent determination of the isotope profiles in the solid by ToF-SIMS. It is shown that a correct description of the diffusion profiles requires the analysis of the diffusion through the surface space-charge into the material's bulk. Surface exchange coefficients, space-charge potentials and bulk diffusion coefficients are analysed as a function of oxygen partial pressure and temperature. The

  1. Bismuth-Based Quadruple Therapy with Bismuth Subcitrate, Metronidazole, Tetracycline and Omeprazole in the Eradication of Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    Raymond Lahaie

    2001-01-01

    Full Text Available BACKGROUND: A previous study showed that 14 days of qid bismuth-based triple therapy with tetracycline 500 mg, metronidazole 250 mg and colloidal bismuth subcitrate 120 mg resulted in excellent Helicobacter pylori eradication rates (89.5%. The present study looked at a shorter treatment period by adding omeprazole and by reducing the dose of tetracycline.

  2. Quantum oscillations of conductivity in bismuth wires

    International Nuclear Information System (INIS)

    Condrea, Elena

    2011-01-01

    Measurements of the resistance of bismuth nanowires with several diameters and different quality reveal oscillations on the dependence of resistance under uniaxial strain at T = 4.2 K. Amplitude of oscillations is significant (38 %) at helium temperature and becomes smearing at T = 77 K. Observed oscillations originate from quantum size effect. A simple evaluation of period of oscillations allows us to identify the groups of carriers involved in transport. Calculated periods of 42.2 and 25.9 nm satisfy approximately the ratio 2:1 for two experimentally observed sets of oscillations from light and heavy electrons.

  3. An evaluated neutronic data file for bismuth

    International Nuclear Information System (INIS)

    Guenther, P.T.; Lawson, R.D.; Meadows, J.W.; Smith, A.B.; Smith, D.L.; Sugimoto, M.; Howerton, R.J.

    1989-11-01

    A comprehensive evaluated neutronic data file for bismuth, extending from 10 -5 eV to 20.0 MeV, is described. The experimental database, the application of the theoretical models, and the evaluation rationale are outlined. Attention is given to uncertainty specification, and comparisons are made with the prior ENDF/B-V evaluation. The corresponding numerical file, in ENDF/B-VI format, has been transmitted to the National Nuclear Data Center, Brookhaven National Laboratory. 106 refs., 10 figs., 6 tabs

  4. Optical Properties of Bismuth Tellurite Based Glass

    Directory of Open Access Journals (Sweden)

    Hooi Ming Oo

    2012-04-01

    Full Text Available A series of binary tellurite based glasses (Bi2O3x (TeO2100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO. The Fourier transform infrared spectroscopy (FTIR results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases.

  5. Optical Properties of Bismuth Tellurite Based Glass

    Science.gov (United States)

    Oo, Hooi Ming; Mohamed-Kamari, Halimah; Wan-Yusoff, Wan Mohd Daud

    2012-01-01

    A series of binary tellurite based glasses (Bi2O3)x (TeO2)100−x was prepared by melt quenching method. The density, molar volume and refractive index increase when bismuth ions Bi3+ increase, this is due to the increased polarization of the ions Bi3+ and the enhanced formation of non-bridging oxygen (NBO). The Fourier transform infrared spectroscopy (FTIR) results show the bonding of the glass sample and the optical band gap, Eopt decreases while the refractive index increases when the ion Bi3+ content increases. PMID:22605999

  6. Feasibility of preparing patterned molybdenum coatings on bismuth telluride thermoelectric modules.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Hall, Aaron Christopher; Miller, Stephen Samuel; Knight, Marlene E.; LePage, William S.; Sobczak, Catherine Elizabeth.; Wesolowski, Daniel Edward

    2013-09-01

    Molybdenum electrical interconnects for thermoelectric modules were produced by air plasma spraying a 30%CE%BCm size molybdenum powder through a laser-cut Kapton tape mask. Initial feasibility demonstrations showed that the molybdenum coating exhibited excellent feature and spacing retention (~170%CE%BCm), adhered to bismuth-telluride, and exhibited electrical conductivity appropriate for use as a thermoelectric module interconnect. A design of experiments approach was used to optimize air plasma spray process conditions to produce a molybdenum coating with low electrical resistivity. Finally, a molybdenum coating was successfully produced on a fullscale thermoelectric module. After the addition of a final titanium/gold layer deposited on top of the molybdenum coating, the full scale module exhibited an electrical resistivity of 128%CE%A9, approaching the theoretical resistivity value for the 6mm module leg of 112%CE%A9. Importantly, air plasma sprayed molybdenum did not show significant chemical reaction with bismuth-telluride substrate at the coating/substrate interface. The molybdenum coating microstructure consisted of lamellar splats containing columnar grains. Air plasma sprayed molybdenum embedded deeply (several microns) into the bismuth-telluride substrate, leading to good adhesion between the coating and the substrate. Clusters of round pores (and cracks radiating from the pores) were found immediately beneath the molybdenum coating. These pores are believed to result from tellurium vaporization during the spray process where the molten molybdenum droplets (2623%C2%B0C) transferred their heat of solidification to the substrate at the moment of impact. Substrate cooling during the molybdenum deposition process was recommended to mitigate tellurium vaporization in future studies.

  7. The tide in the seas of Titan

    International Nuclear Information System (INIS)

    Sagan, C.; Dermott, S.F.

    1982-01-01

    It is argued that, if Titan has oceans consisting of liquid methane, then the present high eccentricity of the satellite necessitates that the depth would be greater than 400 m. Such an ocean should be detectable by radar. The effects of tidal dissipation due to the possible existence of an ocean on Titan are considered. (author)

  8. Liquid Lead-Bismuth Materials Test Loop

    International Nuclear Information System (INIS)

    Tcharnotskaia, Valentina; Ammerman, Curtt; Darling, Timothy; King, Joe; Li, Ning; Shaw, Don; Snodgrass, Leon; Woloshun, Keith

    2002-01-01

    We designed and built the Liquid Lead-Bismuth Materials Test Loop (MTL) to study the materials behavior in a flow of molten lead-bismuth eutectic (LBE). In this paper we present a description of the loop with main components and their functions. Stress distribution in the piping due to sustained, occasional and expansion loads is shown. The loop is designed so that a difference of 100 deg. C can be attained between the coldest and the hottest parts at a nominal flow rate of 8.84 GPM. Liquid LBE flow can be activated by a mechanical sump pump or by natural convection. In order to maintain a self-healing protective film on the surface of the stainless steel pipe, a certain concentration of oxygen has to be maintained in the liquid metal. We developed oxygen sensors and an oxygen control system to be implemented in the loop. The loop is outfitted with a variety of instruments that are controlled from a computer based data acquisition system. Initial experiments include preconditioning the loop, filling it up with LBE, running at uniform temperature and tuning the oxygen control system. We will present some preliminary results and discuss plans for the future tests. (authors)

  9. What is the structure of liquid Bismuth?

    International Nuclear Information System (INIS)

    Caspi, El'ad N; Greenberg, Yaron; Yahel, Eyal; Beuneu, Brigitte; Makov, Guy

    2012-01-01

    The structure of liquid Bismuth is probably the best-studied among elemental liquid metals because of a combination of the interesting physical properties of Bismuth and its excellent neutron scattering properties. Over the last six decades there have been more than 10 independent studies of the structure of liquid Bi, near the melting temperature. This remarkable number of measurements provides an opportunity to compare these results and to analyze the different sources of error contributing to the calculated pair distribution function. In the present contribution we analyze possible sources of error by varying the analysis procedure for a given measurement. By repeating a previous measurement in a new experimental configuration we demonstrate that an invariant (i.e. up to an absolute error) structure factor can be obtained. Transforming the structure factor into the radial distribution introduces new sources of error which causes the scatter to be greater than that required to resolve issues such as the existence of liquid-liquid phase transitions in Bi and to obtain correlation between thermo-physical properties and structure. We consider the contribution of different parameters when transforming the structure factor to the radial distribution function.

  10. Study of point defects in bismuth

    International Nuclear Information System (INIS)

    Bois, P.

    1987-03-01

    Single crystalline samples of bismuth, pure and n or p - doped by adding tellurium or tin, were electron irradiated at low temperature (4.2 K and 20 K). In the energy range 0.7 - 2.5 MeV, a displacement threshold energy of 13 eV and an athermal recombination volume of 150 atomic volumes were determined. Joint measurements of resistivity, magnetotransport and positron annihilation enabled to precised the nature of the annealing stages: 40-50 K, free migration of interstitials; 90-120 K long range migration of vacancy. Point defects have according to their nature a different effect on the electronic properties of bismuth: isolated Frenkel pairs are globally donnors with a charge of + 0.16 e- and the vacancy is donnor, which seems to attribute to it a negative formation volume. A simple model with non-deformating bands is no longer sufficient to explain the behaviour under irradiation: one has to take into account an acceptor level with a charge of - 0,27 e-, linked to the cascade-type defects and resonating with the valence band. It's position in the band overlap and it's width (8 meV) could be precised. In first approximation this coupling with less mobile carriers does not affect the simple additive rule which exists for relaxation times. Some yet obscure magnetic properties seem to be linked to this defect level [fr

  11. Development of lead-bismuth coolant technology for nuclear device

    International Nuclear Information System (INIS)

    Kamata, Kin-ya; Kitano, Teruaki; Ono, Mikinori

    2004-01-01

    Liquid lead-bismuth is a promising material as a future fast reactor coolant or an intensive neutron source material for accelerator driven transmutation system (ADS). To develop nuclear plants and their installations using lead-bismuth coolant for practical use, both coolant technologies, inhabitation process of steels and quality control of coolant, and total operation system for liquid lead-bismuth plants are required. Based on the experience of liquid metal coolant, Mitsui Engineering and Shipbuilding Co., Ltd. (MES) has completed the liquid lead-bismuth forced circulation loop and has acquired various engineering data on main components including economizer. As a result of tis operation, MES has developed key technologies of lead-bismuth coolant such as controlling of oxygen content in lead-bismuth and a purification of lead-bismuth coolant. MES participated in the national project, ''The Development of Accelerator Driven Transmutation System'', together with JAERI (Japan Atomic Energy Research Institute) and started corrosion test for beam window of ADS. (author)

  12. Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics

    Science.gov (United States)

    Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

    2009-03-01

    Bi2O3-doped barium zirconate titanate ceramics, Ba1-xBix(Zr0.05Ti0.95)O3, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi3+ substitutes A-site ion, and thereafter with higher Bi3+ content, it enters the B-site sub lattice. Substitution of Bi3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

  13. Ferroelectric relaxor behaviour and impedance spectroscopy of Bi2O3-doped barium zirconium titanate ceramics

    International Nuclear Information System (INIS)

    Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K; Sreenivas, K

    2009-01-01

    Bi 2 O 3 -doped barium zirconate titanate ceramics, Ba 1-x Bi x (Zr 0.05 Ti 0.95 )O 3 , have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi 3+ substitutes A-site ion, and thereafter with higher Bi 3+ content, it enters the B-site sub lattice. Substitution of Bi 3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

  14. A simple fast microwave-assisted synthesis of thermoelectric bismuth telluride nanoparticles from homogeneous reaction-mixture

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Susmita [Jadavpur University, Department of Instrumentation Science (India); Das, Rashmita [Jadavpur University, Department of Instrumentation and Electronics Engineering (India); Bhar, Radhaballabh [Jadavpur University, Department of Instrumentation Science (India); Bandyopadhyay, Rajib [Jadavpur University, Department of Instrumentation and Electronics Engineering (India); Pramanik, Panchanan, E-mail: pramanik1946@gmail.com [GLA University, Department of Chemistry and Nanoscience (India)

    2017-02-15

    A new simple chemical method for synthesis of nanocrystalline bismuth telluride (Bi{sub 2}Te{sub 3}) has been developed by microwave assisted reduction of homogeneous tartrate complexes of bismuth and tellurium metal ions with hydrazine. The reaction is performed at pH 10. The nano-crystallites have rhombohedral phase identified by XRD. The size distribution of nanoparticle is narrow and it ranges between 50 to 70 nm. FESEM shows that the fine powders are composed of small crystallites. The TEM micrographs show mostly deformed spherical particles and the lattice fringes are found to be 0.137 nm. Energy dispersive X-ray spectroscopy (EDX) analysis shows the atomic composition ratio between bismuth and tellurium is 2:3. Thermoelectric properties of the materials are studied after sintering by spark plasma sintering method (SPS). The grain size of the material after sintering is in the nanometer range. The material shows enhanced Seebeck coefficient and electrical conductivity value at 300 K. The figure of merit is found to be 1.18 at 300 K.

  15. Properties of Nanostructure Bismuth Telluride Thin Films Using Thermal Evaporation

    Directory of Open Access Journals (Sweden)

    Swati Arora

    2017-01-01

    Full Text Available Bismuth telluride has high thermoelectric performance at room temperature; in present work, various nanostructure thin films of bismuth telluride were fabricated on silicon substrates at room temperature using thermal evaporation method. Tellurium (Te and bismuth (Bi were deposited on silicon substrate in different ratio of thickness. These films were annealed at 50°C and 100°C. After heat treatment, the thin films attained the semiconductor nature. Samples were studied by X-ray diffraction (XRD and scanning electron microscopy (SEM to show granular growth.

  16. Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice

    DEFF Research Database (Denmark)

    Jackson, Petra; Halappanavar, Sabina; Hougaard, Karin Sorig

    2013-01-01

    We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA...... strand breaks using the comet assay in bronchoalveolar lavage (BAL) cells and livers of the time-mated mice (5 and 26-27 days after inhalation exposure), and in livers of the offspring (post-natal days (PND) 2 and 22). We also analysed hepatic gene expression in newborns using DNA microarrays. UV-Titan...

  17. Effect of Nb on barium titanate prepared from citrate solutions

    Directory of Open Access Journals (Sweden)

    Stojanović Biljana D.

    2002-01-01

    Full Text Available The influence of the addition of dopants on the microstructure development and electrical properties of BaTiO3 doped with 0.2, 0.4, 0.6, 0.8 mol% of Nb and 0.01 mol% of Mn based compounds was studied. Doped barium titanate was prepared using the polymeric precursor method from citrate solutions. The powders calcined at 700°C for 4 hours were analysed by infrared (IR spectroscopy to verify the presence of carbonates, and by X-ray diffraction (XRD for phase formation. The phase composition, microstructure and dielectric properties show a strong dependence on the amount of added niobium.

  18. Foundations of powder metallurgy

    International Nuclear Information System (INIS)

    Libenson, G.A.

    1987-01-01

    Consideration is being given to physicochemical foundations and technology of metal powders, moulding and sintering of bars, made of them or their mixtures with nonmetal powders. Data on he design of basic equipment used in the processes of powder metallurgy and its servicing are presented. General requirements of safety engineering when fabricating metal powders and products of them are mentioned

  19. Safe prescribing: a titanic challenge.

    Science.gov (United States)

    Routledge, Philip A

    2012-10-01

    The challenge to achieve safe prescribing merits the adjective 'titanic'. The organisational and human errors leading to poor prescribing (e.g. underprescribing, overprescribing, misprescribing or medication errors) have parallels in the organisational and human errors that led to the loss of the Titanic 100 years ago this year. Prescribing can be adversely affected by communication failures, critical conditions, complacency, corner cutting, callowness and a lack of courage of conviction, all of which were also factors leading to the Titanic tragedy. These issues need to be addressed by a commitment to excellence, the final component of the 'Seven C's'. Optimal prescribing is dependent upon close communication and collaborative working between highly trained health professionals, whose role is to ensure maximum clinical effectiveness, whilst also protecting their patients from avoidable harm. Since humans are prone to error, and the environments in which they work are imperfect, it is not surprising that medication errors are common, occurring more often during the prescribing stage than during dispensing or administration. A commitment to excellence in prescribing includes a continued focus on lifelong learning (including interprofessional learning) in pharmacology and therapeutics. This should be accompanied by improvements in the clinical working environment of prescribers, and the encouragement of a strong safety culture (including reporting of adverse incidents as well as suspected adverse drug reactions whenever appropriate). Finally, members of the clinical team must be prepared to challenge each other, when necessary, to ensure that prescribing combines the highest likelihood of benefit with the lowest potential for harm. © 2012 The Author. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

  20. This is Commercial Titan Inc.

    Science.gov (United States)

    Van Rensselaer, F. L.; Slovikoski, R. D.; Abels, T. C.

    Out of a quarter-century heritage of eminently successful expendable launch vehicle history with the U.S. government, a commercial launch services enterprise which challenges the corporation as well as the competition has been launched within the Martin Marietta Corporation. This paper is an inside look at the philosophy, structure, and success of the new subsidiary, Commercial Titan Inc., which is taking on its U.S. and foreign rocket-making competitors to win a share of the international communication satellite market as well as the U.S. government commercial launch services market.

  1. On the use of bismuth as a neutron and gamma ray filter

    International Nuclear Information System (INIS)

    Adib, M.; Kilany, M.

    2003-01-01

    A formula is given which, for neutron energies in the range 10 -4 < E<10 eV, permits calculation of the nuclear capture, thermal diffuse and bragg scattering cross-sections as a function of bismuth temperature crystalline form. Computer programs have been developed which allow calculations for the Bi rhombohedral structure in its poly-crystalline form and its equivalent hexagonal close-packed structure. Calculated total neutron cross-sections for poly-crystalline Bi at different temperatures were compared with measured values. Overall agreement is indicated between the formula fits and experimental data. Agreement was also obtained for values of Bi-single crystals, at room and liquid nitrogen temperatures. A feasibility study for use of Bi in powdered form, as a spread temperature and cutting plane for efficient transmission of thermal-reactor neutrons, and also for rejection of accompanying fast neutrons and gamma rays

  2. Sol-Gel Synthesis and Characterization of Cubic Bismuth Zinc Niobium Oxide Nanopowders

    Directory of Open Access Journals (Sweden)

    Ganchimeg Perenlei

    2014-01-01

    Full Text Available Bismuth zinc niobium oxide (BZN was successfully synthesized by a diol-based sol-gel reaction utilizing metal acetate and alkoxide precursors. Thermal analysis of a liquid suspension of precursors suggests that the majority of organic precursors decompose at temperatures up to 150°C, and organic free powders form above 350°C. The experimental results indicate that a homogeneous gel is obtained at about 200°C and then converts to a mixture of intermediate oxides at 350–400°C. Finally, single-phased BZN powders are obtained between 500 and 900°C. The degree of chemical homogeneity as determined by X-ray diffraction and EDS mapping is consistent throughout the samples. Elemental analysis indicates that the atomic ratio of metals closely matches a Bi1.5ZnNb1.5O7 composition. Crystallite sizes of the BZN powders calculated from the Scherrer equation are about 33–98 nm for the samples prepared at 500–700°C, respectively. The particle and crystallite sizes increase with increased sintering temperature. The estimated band gap of the BZN nanopowders from optical analysis is about 2.60–2.75 eV at 500-600°C. The observed phase formations and measured results in this study were compared with those of previous reports.

  3. Fundamentals of powder metallurgy

    International Nuclear Information System (INIS)

    Khan, I.H.; Qureshi, K.A.; Minhas, J.I.

    1988-01-01

    This book is being presented to introduce the fundamentals of technology of powder metallurgy. An attempt has been made to present an overall view of powder metallurgy technology in the first chapter, whereas chapter 2 to 8 deal with the production of metal powders. The basic commercial methods of powder production are briefly described with illustrations. Chapter 9 to 12 describes briefly metal powder characteristics and principles of testing, mixing, blending, conditioning, compaction and sintering. (orig./A.B.)

  4. Ultrasonic investigations of some bismuth borate glasses doped with ...

    Indian Academy of Sciences (India)

    Keywords. Bismuth borate glasses; elastic moduli; Makishima–Mackenzie model. 1. Introduction ... former because of the small field strength of Bi3+ ion. Bi2O3 ..... Typically, when the material undergoes a phase change, the value of the.

  5. Studies on bismuth carboxylates—synthesis and characterization of ...

    Indian Academy of Sciences (India)

    crystalline modification (4 ) of the previously reported coordination polymer, bismuth tris(picolinate), [Bi(2– .... no significant change in the IR spectrum or the melting behaviour between 4 .... lens et al.7 There are moderate differences in the.

  6. Chemical investigation of Titan and Triton tholins

    Science.gov (United States)

    Mcdonald, Gene D.; Thompson, W. R.; Heinrich, Michael; Khare, Bishun N.; Sagan, Carl

    1994-01-01

    We report chromatographic and spectroscopic analyses of both Titan and Triton tholins, organic solids made from the plasma irradiation of 0.9:0.1 and 0.999:0.001 N2/CH4 gas mixtures, respectively. The lower CH4 mixing ratio leads to a nitrogen-richer tholin (N/C greater than 1), probably including nitrogen heterocyclic compounds. Unlike Titan tholin, bulk Triton tholin is poor in nitriles. From high-pressure liquid chromatography, ultraviolet and infrared spectroscopy, and molecular weight estimation by gel filtration chromatography, we conclude that (1) several H2O-soluble fractions, each with distinct UV and IR spectral signatures, are present, (2) these fractions are not identical in the two tholins, (3) the H2O-soluble fractions of Titan tholins do not contain significant amounts of nitriles, despite the major role of nitriles in bulk Titan tholin, and (4) the H2O-soluble fractions of both tholins are mainly molcules containing about 10 to 50 (C + N) atoms. We report yields of amino acids upon hydrolysis of Titan and Triton tholins. Titan tholin is largely insoluble in the putative hydrocarbon lakes or oceans on Titan, but can yield the H2O-soluble species investigated here upon contact with transient (e.g., impact-generated) liquid water.

  7. Chemistry and evolution of Titan's atmosphere

    International Nuclear Information System (INIS)

    Strobel, D.F.

    1982-01-01

    The chemistry and evolution of Titan's atmosphere is reviewed in the light of the scientific findings from the Voyager mission. It is argued that the present N 2 atmosphere may be Titan's initial atmosphere rather than photochemically derived from an original NH 3 atmosphere. The escape rate of hydrogen from Titan is controlled by photochemical production from hydrocarbons. CH 4 is irreversibly converted to less hydrogen rich hydrocarbons, which over geologic time accumulate on the surface to a layer thickness of approximately 0.5 km. Magnetospheric electrons interacting with Titan's exosphere may dissociate enough N 2 into hot, escaping N atoms to remove approximately 0.2 of Titan's present atmosphere over geologic time. The energy dissipation of magnetospheric electrons exceeds solar e.u.v. energy deposition in Titan's atmosphere by an order of magnitude and is the principal driver of nitrogen photochemistry. The environmental conditions in Titan's upper atmosphere are favorable to building up complex molecules, particularly in the north polar cap region. (author)

  8. Flotation atomic absorption determination of bismuth in nonferrous metal alloys

    International Nuclear Information System (INIS)

    Ososkov, V.K.; Plintus, A.M.; Kornelli, M.Eh.; Zakhariya, A.N.; Lozanova, E.V.

    1986-01-01

    Technique of flotation concentration and atomic absorption determination of bismuth microquantities in alloys on the basis of copper and zinc has been developed. Fine-dispersed EhDEh-10P anionite was used as a carrier in flotation concentration. State standard samples (SSS) of brasses and German silver were used as analysed objects. Effect of macrocomponents on the results of bismuth content determination has been studied. Satisfactory coincidence of the results obtained and SSS certificates is shown

  9. Platinum-Bismuth Bimetallic Catalysts: Synthesis, Characterization and Applications

    OpenAIRE

    Saucedo, Jose A, Jr; Xiao, Yang; Varma, Arvind

    2015-01-01

    Bimetallic catalysts have been explored and shown to exhibit unique characteristics which are not present in monometallic catalysts. Platinum is well known as an effective catalyst for oxidation and reduction reactions, and it can be made more effective when bismuth is introduced as a promotor. Thus, the effectiveness of the Pt-Bi catalyst was demonstrated in prior work. What is not clear, however, is the mechanism behind the catalyst function; why addition of bismuth to platinum decreases de...

  10. Titan the earth-like moon

    CERN Document Server

    Coustenis, Athena

    1999-01-01

    This is the first book to deal with Titan, one of the most mysterious bodies in the solar system. The largest satellite of the giant planet Saturn, Titan is itself larger than the planet Mercury, and is unique in being the only known moon with a thick atmosphere. In addition, its atmosphere bears a startling resemblance to the Earth's, but is much colder.The American and European space agencies, NASA and ESA, have recently combined efforts to send a huge robot spacecraft to orbit Saturn and land on Titan. This book provides the background to this, the greatest deep space venture of our time, a

  11. The greenhouse and antigreenhouse effects on Titan

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1991-01-01

    The parallels between the atmospheric thermal structure of the Saturnian satellite Titan and the hypothesized terrestrial greenhouse effect can serve as bases for the evaluation of competing greenhouse theories. Attention is presently drawn to the similarity between the roles of H2 and CH4 on Titan and CO2 and H2O on earth. Titan also has an antigreenhouse effect due to a high-altitude haze layer which absorbs at solar wavelengths, while remaining transparent in the thermal IR; if this haze layer were removed, the antigreenhouse effect would be greatly reduced, exacerbating the greenhouse effect and raising surface temperature by over 20 K.

  12. The commercial evolution of the Titan program

    Science.gov (United States)

    Isakowitz, Steven

    1988-07-01

    The present status evaluation of proprietary efforts to turn the once exclusively government-requirements-oriented Titan launch vehicle into a successful commercial competitor is divided into three phases. The first phase notes recent changes in U.S. space transportation policy and the Titan configurations evaluated for commercial feasibility. The second phase is a development history for the current vehicle's marketing organization and the right-to-use agreement for a launch site. Phase three projects the prospective marketing climate for a commercial Titan vehicle and its planned improvements.

  13. Titan's organic chemistry: Results of simulation experiments

    Science.gov (United States)

    Sagan, Carl; Thompson, W. Reid; Khare, Bishun N.

    1992-01-01

    Recent low pressure continuous low plasma discharge simulations of the auroral electron driven organic chemistry in Titan's mesosphere are reviewed. These simulations yielded results in good accord with Voyager observations of gas phase organic species. Optical constants of the brownish solid tholins produced in similar experiments are in good accord with Voyager observations of the Titan haze. Titan tholins are rich in prebiotic organic constituents; the Huygens entry probe may shed light on some of the processes that led to the origin of life on Earth.

  14. In situ electron beam irradiated rapid growth of bismuth nanoparticles in bismuth-based glass dielectrics at room temperature

    International Nuclear Information System (INIS)

    Singh, Shiv Prakash; Karmakar, Basudeb

    2011-01-01

    In this study, in situ control growth of bismuth nanoparticles (Bi 0 NPs) was demonstrated in bismuth-based glass dielectrics under an electron beam (EB) irradiation at room temperature. The effects of EB irradiation were investigated in situ using transmission electron microscopy (TEM), selected-area electron diffraction and high-resolution transmission electron microscopy. The EB irradiation for 2–8 min enhanced the construction of bismuth nanoparticles with a rhombohedral structure and diameter of 4–9 nm. The average particle size was found to increase with the irradiation time. Bismuth metal has a melting point of 271 °C and this low melting temperature makes easy the progress of energy induced structural changes during in situ TEM observations. This is a very useful technique in nano-patterning for integrated optics and other applications.

  15. TSSM: The in situ exploration of Titan

    Science.gov (United States)

    Coustenis, A.; Lunine, J. I.; Lebreton, J. P.; Matson, D.; Reh, K.; Beauchamp, P.; Erd, C.

    2008-09-01

    The Titan Saturn System Mission (TSSM) mission was born when NASA and ESA decided to collaborate on two missions independently selected by each agency: the Titan and Enceladus mission (TandEM), and Titan Explorer, a 2007 Flagship study. TandEM, the Titan and Enceladus mission, was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call. The mission concept is to perform remote and in situ investigations of Titan primarily, but also of Enceladus and Saturn's magentosphere. The two satellites are tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TSSM will study Titan as a system, including its upper atmosphere, the interactions with the magnetosphere, the neutral atmosphere, surface, interior, origin and evolution, as well as the astrobiological potential of Titan. It is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini- Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time for Titan, several close flybys of Enceladus). One overarching goal of the TSSM mission is to explore in situ the atmosphere and surface of Titan. In the current mission architecture, TSSM consists of an orbiter (under NASA's responsibility) with a large host of instruments which would perform several Enceladus and Titan flybys before stabilizing in an orbit around Titan alone, therein delivering in situ elements (a Montgolfière, or hot air balloon, and a probe/lander). The latter are being studied by ESA. The balloon will circumnavigate Titan above the equator at an altitude of about 10 km for several months. The

  16. Analysis of isothermal sintering of zinc-titanate doped with MgO

    Directory of Open Access Journals (Sweden)

    Obradović N.

    2007-01-01

    Full Text Available The aim of this work was analysis of isothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5% were mechanically activated 15 minutes in a planetary ball mill. The powders obtained were pressed under different pressures and the results were fitted with a phenomenological compacting equation. Isothermal sintering was performed in air for 120 minutes at four different temperatures. Structural characterization of ZnO-TiO2-MgO system after milling was performed at room temperature using XRPD measurements. DTA measurements showed different activation energies for pure and doped ZnO-TiO2 systems. Thus addition of MgO stabilizes the crystal structure of zinc titanate.

  17. Titan's Atmospheric Dynamics and Meteorology

    Science.gov (United States)

    Flasar, F. M.; Baines, K. H.; Bird, M. K.; Tokano, T.; West, R. A.

    2008-01-01

    Titan, after Venus, is the second example of an atmosphere with a global cyclostrophic circulation in the solar system, but a circulation that has a strong seasonal modulation in the middle atmosphere. Direct measurement of Titan's winds, particularly observations tracking the Huygens probe at 10degS, indicate that the zonal winds are generally in the sense of the satellites rotation. They become cyclostrophic approx. 35 km above the surface and generally increase with altitude, with the exception of a sharp minimum centered near 75 km, where the wind velocity decreases to nearly zero. Zonal winds derived from the temperature field retrieved from Cassini measurements, using the thermal wind equation, indicate a strong winter circumpolar vortex, with maximum winds at mid northern latitudes of 190 ms-' near 300 km. Above this level, the vortex decays. Curiously, the zonal winds and temperatures are symmetric about a pole that is offset from the surface pole by approx.4 degrees. The cause of this is not well understood, but it may reflect the response of a cyclostrophic circulation to the offset between the equator, where the distance to the rotation axis is greatest, and the solar equator. The mean meridional circulation can be inferred from the temperature field and the meridional distribution of organic molecules and condensates and hazes. Both the warm temperatures in the north polar region near 400 km and the enhanced concentration of several organic molecules suggests subsidence there during winter and early spring. Stratospheric condensates are localized at high northern latitudes, with a sharp cut-off near 50degN. Titan's winter polar vortex appears to share many of the same characteristics of winter vortices on Earth-the ozone holes. Global mapping of temperatures, winds, and composition in he troposphere, by contrast, is incomplete. The few suitable discrete clouds that have bee found for tracking indicate smaller velocities than aloft, consistent with the

  18. Titanic või turist? / Karin Paulus

    Index Scriptorium Estoniae

    Paulus, Karin, 1975-

    2006-01-01

    Tallinnas Tartu maanteel asuva endise Turisti poe (arhitektid Peep Jänes, Henno Sepmann) asemele tahavad hoone omanikud ehitada kõrghoone nimega Titanic. Hoone ajutine võtmine muinsuskaitse alla on põhjustanud kohtuvaidluse

  19. Titan Submarine: Exploring the Depths of Kraken

    Data.gov (United States)

    National Aeronautics and Space Administration — Titan is unique in the outer solar system in that it is the only one of the bodies outside the Earth with liquid lakes and seas on its surface. The Titanian seas,...

  20. Aluminum titanate crucible for molten uranium

    International Nuclear Information System (INIS)

    Asbury, J.J.

    1975-01-01

    An improved crucible for molten uranium is described. The crucible or crucible liner is formed of aluminum titanate which essentially eliminates contamination of uranium and uranium alloys during molten states thereof. (U.S.)

  1. Future Exploration of Titan and Enceladus

    Science.gov (United States)

    Matson, D. L.; Coustenis, A.; Lunine, J.; Lebreton, J.; Reh, K.; Beauchamp, P.

    2009-05-01

    The future exploration of Titan and Enceladus has become very important for the planetary community. The study conducted last year of the Titan Saturn System Mission (TSSM) led to an announcement in which ESA and NASA prioritized future OPF missions, stating that TSSM is planned after EJSM (for details see http://www.lpi.usra.edu/opag/). TSSM consists of a TSSM Orbiter that would carry two in situ elements: the Titan Montgolfiere hot air balloon and the Titan Lake Lander. The mission could launch in the 2023-2025 timeframe on a trajectory to arrive ~9 years later for a 4-year mission in the Saturn system. Soon after arrival at Saturn, the montgolfiere would be delivered to Titan to begin its mission of airborne, scientific observations of Titan from an altitude of about 10 km. The montgolfiere would have a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) power system and would be designed to last at least 6-12 months in Titan's atmosphere. With the predicted winds and weather, that would be sufficient to circumnavigate the globe! On a subsequent fly-by, the TSSM orbiter would release the Lake Lander on a trajectory toward Titan for a targeted entry. It would descend through the atmosphere making scientific measurements, much like Huygens did, and then land and float on one of Titan's seas. This would be its oceanographic phase, making a physical and chemical assessment of the sea. The Lake Lander would operate 8-10 hours until its batteries become depleted. Following the delivery of the in situ elements, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes in situ sampling of Enceladus' plumes as well as Titan flybys. After the Saturn system tour, the TSSM orbiter would enter orbit around Titan for a global survey phase. Synergistic and coordinated observations would be carried out between the TSSM orbiter and the in situ elements. The scientific requirements were developed by the international TSSM Joint Science Definition

  2. Crystalline perfection and mechanical investigations on vertical Bridgman grown Bismuth telluride (Bi{sub 2}Te{sub 3}) single crystals for thermoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, Anuj [Academy of Scientific and Innovative Research, CSIR- National Physical Laboratory, New Delhi 110012 (India); X-ray Analysis and Crystal Growth Section, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Vijayan, N., E-mail: nvijayan@nplindia.org [X-ray Analysis and Crystal Growth Section, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Singh, Budhendra [TEMA-NRD, Mechanical Engineering Department and Aveiro Institute of Nanotechnology (AIN), University of Aveiro, 3810-193 Aveiro (Portugal); Thukral, Kanika [Academy of Scientific and Innovative Research, CSIR- National Physical Laboratory, New Delhi 110012 (India); X-ray Analysis and Crystal Growth Section, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Maurya, K.K. [X-ray Analysis and Crystal Growth Section, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2016-03-07

    High efficiency thermoelectric materials plays a vital role in power generation and refrigeration applications. Bismuth telluride (Bi{sub 2}Te{sub 3}) is one among them. In the present work single crystal of bismuth telluride was grown using vertical Bridgman technique. The phase of grown crystals was analysed using a powder X-ray diffractometer. Quality of the grown crystal was assessed by using high resolution X-ray diffractometer and observed that it is fairly good. Further mechanical investigations on grown crystal was carried out using nano-indentation technique and various mechanical properties like hardness, stiffness and Young’s modulus were evaluated. Observed results clearly indicate its suitability for thermoelectric applications.

  3. The rotation of Titan and Ganymede

    Science.gov (United States)

    Van Hoolst, Tim; Coyette, Alexis; Baland, Rose-Marie; Trinh, Antony

    2016-10-01

    The rotation rates of Titan and Ganymede, the largest satellites of Saturn and Jupiter, are on average equal to their orbital mean motion. Here we discuss small deviations from the average rotation for both satellites and evaluate the polar motion of Titan induced by its surface fluid layers. We examine different causes at various time scales and assess possible consequences and the potential of using librations and polar motion as probes of the interior structure of the satellites.The rotation rate of Titan and Ganymede cannot be constant on the orbital time scale as a result of the gravitational torque of the central planet acting on the satellites. Titan is moreover expected to show significant polar motion and additional variations in the rotation rate due to angular momentum exchange with the atmosphere, mainly at seasonal periods. Observational evidence for deviations from the synchronous state has been reported several times for Titan but is unfortunately inconclusive. The measurements of the rotation variations are based on determinations of the shift in position of Cassini radar images taken during different flybys. The ESA JUICE (JUpiter ICy moons Explorer) mission will measure the rotation variations of Ganymede during its orbital phase around the satellite starting in 2032.We report on different theoretical aspects of the librations and polar motion. We consider the influence of the rheology of the ice shell and take into account Cassini measurements of the external gravitational field and of the topography of Titan and similar Galileo data about Ganymede. We also evaluate the librations and polar motion induced by Titan's hydrocarbon seas and use the most recent results of Titan's atmosphere dynamics. We finally evaluate the potential of rotation variations to constrain the satellite's interior structure, in particular its ice shell and ocean.

  4. Titan Orbiter with Aerorover Mission (TOAM)

    Science.gov (United States)

    Sittler, Edward C.; Cooper, J. F.; Mahaffey, P.; Esper, J.; Fairbrother, D.; Farley, R.; Pitman, J.; Kojiro, D. R.; TOAM Team

    2006-12-01

    We propose to develop a new mission to Titan called Titan Orbiter with Aerorover Mission (TOAM). This mission is motivated by the recent discoveries of Titan, its atmosphere and its surface by the Huygens Probe, and a combination of in situ, remote sensing and radar mapping measurements of Titan by the Cassini orbiter. Titan is a body for which Astrobiology (i.e., prebiotic chemistry) will be the primary science goal of any future missions to it. TOAM is planned to use an orbiter and balloon technology (i.e., aerorover). Aerobraking will be used to put payload into orbit around Titan. The Aerorover will probably use a hot air balloon concept using the waste heat from the MMRTG 500 watts. Orbiter support for the Aerorover is unique to our approach for Titan. Our strategy to use an orbiter is contrary to some studies using just a single probe with balloon. Autonomous operation and navigation of the Aerorover around Titan will be required, which will include descent near to the surface to collect surface samples for analysis (i.e., touch and go technique). The orbiter can provide both relay station and GPS roles for the Aerorover. The Aerorover will have all the instruments needed to sample Titan’s atmosphere, surface, possible methane lakes-rivers, use multi-spectral imagers for surface reconnaissance; to take close up surface images; take core samples and deploy seismometers during landing phase. Both active and passive broadband remote sensing techniques will be used for surface topography, winds and composition measurements.

  5. Safe prescribing: a titanic challenge

    Science.gov (United States)

    Routledge, Philip A

    2012-01-01

    The challenge to achieve safe prescribing merits the adjective ‘titanic’. The organisational and human errors leading to poor prescribing (e.g. underprescribing, overprescribing, misprescribing or medication errors) have parallels in the organisational and human errors that led to the loss of the Titanic 100 years ago this year. Prescribing can be adversely affected by communication failures, critical conditions, complacency, corner cutting, callowness and a lack of courage of conviction, all of which were also factors leading to the Titanic tragedy. These issues need to be addressed by a commitment to excellence, the final component of the ‘Seven C's’. Optimal prescribing is dependent upon close communication and collaborative working between highly trained health professionals, whose role is to ensure maximum clinical effectiveness, whilst also protecting their patients from avoidable harm. Since humans are prone to error, and the environments in which they work are imperfect, it is not surprising that medication errors are common, occurring more often during the prescribing stage than during dispensing or administration. A commitment to excellence in prescribing includes a continued focus on lifelong learning (including interprofessional learning) in pharmacology and therapeutics. This should be accompanied by improvements in the clinical working environment of prescribers, and the encouragement of a strong safety culture (including reporting of adverse incidents as well as suspected adverse drug reactions whenever appropriate). Finally, members of the clinical team must be prepared to challenge each other, when necessary, to ensure that prescribing combines the highest likelihood of benefit with the lowest potential for harm. PMID:22738396

  6. Nonthermal atmospheric escape from Mars and Titan

    International Nuclear Information System (INIS)

    Lammer, H.; Bauer, S.J.

    1991-01-01

    Energy flux spectra and particle concentrations of the hot O and N coronae from Mars and Titan, respectively, resulting primarily from dissociative recombination of molecular ions, have been calculated by means of a Monte Carlo method. The calculated energy flux spectra lead to an escape flux null esc ∼ 6 x 10 6 cm -2 s -1 for Mars and null esc ∼ 2 x 10 6 cm -2 s -1 for Titan, corresponding to a mass loss of about 0.14 kg/s for Mars and about 0.3 kg/s for Titan. (The contribution of electron impact ionization on N 2 amounts to only about 25% of Titan's mass loss.) Mass loss via solar and magnetospheric wind is also estimated using newly calculated mass loading limits. The mass loss via ion pickup from the extended hot atom corona for Mars amounts to about 0.25 kg/s (O + ) and for Titan to about 50 g/s (N 2 + or H 2 CN + ). Thus, the total mass loss rate from Mars and Titan is about the same, i.e., 0.4 kg/s

  7. Aluminum powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  8. Nanostructured zirconium titanate fibers prepared by particulate sol–gel and cellulose templating techniques

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, P. [Helmerich Advanced Technology Research Center, School of Electrical and Computer Engineering, Oklahoma State University, OK 74106 (United States); Salahinejad, E. [Helmerich Advanced Technology Research Center, School of Material Science and Engineering, Oklahoma State University, OK 74106 (United States); Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Blvd., 7134851154 Shiraz (Iran, Islamic Republic of); Kaul, R. [Department of Biochemistry and Microbiology, Center for Health Sciences, Oklahoma State University, OK 74107 (United States); Vashaee, D. [Helmerich Advanced Technology Research Center, School of Electrical and Computer Engineering, Oklahoma State University, OK 74106 (United States); Tayebi, L., E-mail: lobat.tayebi@okstate.edu [Helmerich Advanced Technology Research Center, School of Material Science and Engineering, Oklahoma State University, OK 74106 (United States); School of Chemical Engineering, Oklahoma State University, Stillwater, OK 74078 (United States)

    2013-08-15

    Highlights: •A method to produce zirconium titanate fibers was introduced. •The resultant structure and photocatalytic activity of the fiber were investigated. •The fiber exhibited higher photocatalytic characteristics, compared with the powders. -- Abstract: In this paper, a method for cost-effective production of nanostructured zirconium titanate (ZrTiO{sub 4}) fibers is introduced. In this method, ZrTiO{sub 4} fibers were synthesized by a sol–gel technique using cellulose fibers as the template. The resultant structures were studied by transmission electron microscopy, X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller (BET) analyses. The photocatalytic activity of the fiber was compared to that of ZrTiO{sub 4} powders prepared by the same sol–gel method, in dark and under UVA and UVC radiations. According to the results, after calcination accompanied by the template removal, the ZrTiO{sub 4} fiber consists of uniformly-deposited, crystalline nanoparticles. This nanostructured fiber exhibited a higher surface area and a higher porosity compared with the ZrTiO{sub 4} powders, resulting in considerably higher photocatalytic characteristics, as confirmed by the experiment. The large surface area and the enhanced photocatalytic activity of the ZrTiO{sub 4} fibers also offer applications in sensors and bioactive films.

  9. Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2014-01-01

    We propose new designs of plasmonic modulators, which can beused for dynamic signal switching in photonic integrated circuits. We studyperformance of a plasmonic waveguide modulator with bismuth ferrite as atunable material. The bismuth ferrite core is sandwiched between metalplates (metal...

  10. Controlled synthesis of bismuth oxyiodide toward optimization of photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Chenxing; Ma, Zhijun [State Key Laboratory of Luminescent Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641 (China); Chen, Xiaofeng, E-mail: chenxf@scut.edu.c [Biomaterials Research Institute, School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641 (China); He, Xin [School of Applied Physics and Materials, Wuyi University, Jiangmen 529020 (China); Qiu, Jianrong, E-mail: qjr@scut.edu.cn [State Key Laboratory of Luminescent Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510641 (China)

    2016-11-30

    Highlights: • Different bismuth oxyiodide was synthesized. • The hollow Bi{sub 4}O{sub 5}I{sub 2} microspheres was obtained. • Formation mechanism of the hollow structure was discussed in detail. - Abstract: A new investigation on the variation rule of the structure, morphology, chemical composition and photocatalytic performance of bismuth oxyiodide synthesized by solvothermal method as a function of reaction conditions was performed here. The composition and morphology of the product could be determined by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. The results revealed that the particle size together with content of iodide in bismuth oxyiodide decrease with the increase of the concentration of reaction precursors. Hollow Bi{sub 4}O{sub 5}I{sub 2} microsphere with specific surface area as high as 120.88 m{sup 2} g{sup −1} can be easily synthesized when the concentration of the reaction precursors finally increased to 62.5 mM. Photocatalytic water purification performance of the as-prepared samples was evaluated by using Rhodamine B (RhB) as a model contaminant. The results revealed that the hollow Bi{sub 4}O{sub 5}I{sub 2} exhibited the best performance among all the bismuth oxyodide synthesized here for the degradation of RhB under visible light irradiation. Meanwhile, the formation mechanism of the hierarchical hollow structure of bismuth oxyiodide was investigated by the dissolution-recrystallization mechanism.

  11. Lead- or Lead-bismuth-cooled fast reactors

    International Nuclear Information System (INIS)

    Bouchter, J.C.; Courouau, J.L.; Dufour, P.; Guidez, J.; Latge, C.; Martinelli, L.; Renault, C.; Rimpault, G.

    2014-01-01

    Lead-cooled fast reactors are one of the 6 concepts retained for the 4. generation of nuclear reactors. So far no lead-cooled reactors have existed in the world except lead-bismuth-cooled reactors in soviet submarines. Some problems linked to the use of the lead-bismuth eutectic appeared but were satisfactorily solved by a more rigorous monitoring of the chemistry of the lead-bismuth coolant. Lead presents various advantages as a coolant: no reactivity with water and the air,a high boiling temperature and low contamination when irradiated. The main asset of the lead-bismuth alloy is the drop of the fusion temperature from 327 C degrees to 125 C degrees. The main drawback of using lead (or lead-bismuth) is its high corrosiveness with metals like iron, chromium and nickel. The high corrosiveness of the coolant implies low flow velocities which means a bigger core and consequently a bigger reactor containment. Different research programs in the world (in Europe, Russia and the USA) are reviewed in the article but it appears that the development of this type of reactor requires technological breakthroughs concerning materials and the resistance to corrosion. Furthermore the concept of lead-cooled reactors seems to be associated to a range of low output power because of the compromise between the size of the reactor and its resistance to earthquakes. (A.C.)

  12. Oxygen holes and hybridization in the bismuthates

    Science.gov (United States)

    Khazraie, Arash; Foyevtsova, Kateryna; Elfimov, Ilya; Sawatzky, George A.

    2018-02-01

    Motivated by the recently renewed interest in the superconducting bismuth perovskites, we investigate the electronic structure of the parent compounds A BiO3 (A = Sr, Ba) using ab initio methods and tight-binding (TB) modeling. We use the density functional theory (DFT) in the local density approximation (LDA) to understand the role of various interactions in shaping the A BiO3 band structure near the Fermi level. It is established that interatomic hybridization involving Bi-6 s and O-2 p orbitals plays the most important role. Based on our DFT calculations, we derive a minimal TB model and demonstrate that it can describe the properties of the band structure as a function of lattice distortions, such as the opening of a charge gap with the onset of the breathing distortion and the associated condensation of holes onto a1 g-symmetric molecular orbitals formed by the O-2 pσ orbitals on collapsed octahedra. We also derive a single band model involving the hopping of an extended molecular orbital involving both Bi-6 s and a linear combination of six O-2 p orbitals which provides a very good description of the dispersion and band gaps of the low energy scale bands straddling the chemical potential.

  13. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  14. Tunneling in cuprate and bismuthate superconductors

    International Nuclear Information System (INIS)

    Zasadzinski, J.F.; Huang, Qiang; Tralshawala, N.

    1991-10-01

    Tunneling measurements using a point-contact technique are reported for the following high temperature superconducting oxides: Ba 1-x K x BiO 3 (BKBO), Nd 2-x Ce x CuO 4 (NCCO), Bi 2 Sr 2 CaCu 2 O 7 (BSCCO) and Tl 2 Ba 2 CaCu 2 O x (TBCCO). For the bismuthate, BKBO, ideal, S-I-N tunneling characteristics are observed using a Au tip. The normalized conductance is fitted to a BCS density of states and thermal smearing only proving there is no fundamental limitation in BKBO for device applications. For the cuprates, the normalized conductance displays BCS-like characteristics, but with a broadening larger than from thermal smearing. Energy gap values are presented for each material. For BKBO and NCCO the Eliashberg functions, α 2 F(ω), obtained from the tunneling are shown to be in good agreement with neutron scattering results. Proximity effect tunneling studies are reported for Au/BSCCO bilayers and show that the energy gap of BSCCO can be observed through Au layers up to 600 Angstrom thick

  15. Use of Russian technology of ship reactors with lead-bismuth coolant in nuclear power

    International Nuclear Information System (INIS)

    Zrodnikov, A.V.; Chitaykin, V.I.; Gromov, B.F.; Grigoryv, O.G.; Dedoul, A.V.; Toshinsky, G.I.; Dragunov, Yu.G.; Stepanov, V.S.

    2000-01-01

    The experience of using lead-bismuth coolant in Russian nuclear submarine reactors has been presented. The fundamental statements of the concept of using the reactors cooled by lead-bismuth alloy in nuclear power have been substantiated. The results of developments for using lead bismuth coolant in nuclear power have been presented. (author)

  16. Prognostic Value of Bismuth Typing and Modified T-stage in Hilar Cholangiocarcinoma

    Directory of Open Access Journals (Sweden)

    Shengen Yi

    2015-01-01

    Conclusion: The majority of our patients with HCC were characterized as Subtype IV in Bismuth typing and Stage T3 in modified T-stage. Both Bismuth typing and modified T-stage showed prognostic value in HCC. Compared with Bismuth typing, modified T-stage is a better indicator of the resectability of HCC.

  17. Microstructure and electrical properties of bismuth and bismuth oxide deposited by magnetron sputtering UBM

    International Nuclear Information System (INIS)

    Otalora B, D. M.; Dussan, A.; Olaya F, J. J.

    2015-01-01

    In this work, bismuth (Bi) and bismuth oxide (Bi 2 O 3 ) thin films were prepared, at room temperature, by Sputtering Unbalanced Magnetron (UBM - Unbalance Magnetron) technique under glass substrates. Microstructural and electrical properties of the samples were studied by X-ray diffraction (XRD) and System for Measuring Physical Properties - PPMS (Physical Property Measurement System). Dark resistivity of the material was measured for a temperature range between 100 and 400 K. From the XRD measurements it was observed a polycrystalline character of the Bi associated to the presence of phases above the main peak, 2θ = 26.42 grades and a growth governed by a rhombohedral structure. Crystal parameters were obtained for both compounds, Bi and Bi 2 O 3 . From the analysis of the spectra of the conductivity as a function of temperature, it was established that the transport mechanism that governs the region of high temperature (T>300 K) is thermally activated carriers. From conductivity measurements the activation energies were obtained of 0.0094 eV and 0.015 eV for Bi 2 O 3 and Bi, respectively. (Author)

  18. Spherical rhenium metal powder

    International Nuclear Information System (INIS)

    Leonhardt, T.; Moore, N.; Hamister, M.

    2001-01-01

    The development of a high-density, spherical rhenium powder (SReP) possessing excellent flow characteristics has enabled the use of advanced processing techniques for the manufacture of rhenium components. The techniques that were investigated were vacuum plasma spraying (VPS), direct-hot isostatic pressing (D-HIP), and various other traditional powder metallurgy processing methods of forming rhenium powder into near-net shaped components. The principal disadvantages of standard rhenium metal powder (RMP) for advanced consolidation applications include: poor flow characteristics; high oxygen content; and low and varying packing densities. SReP will lower costs, reduce processing times, and improve yields when manufacturing powder metallurgy rhenium components. The results of the powder characterization of spherical rhenium powder and the consolidation of the SReP are further discussed. (author)

  19. Reduced-graphene-oxide-and-strontium-titanate-based double ...

    Indian Academy of Sciences (India)

    GO)/strontium titanate were pre- ... R-GO and strontium titanate were synthesized and characterized before ... Microwave absorption capabilities of the composite absorbers were investigated using a .... was backed with a conducting metal sheet.

  20. Selections from 2017: Discoveries in Titan's Atmosphere

    Science.gov (United States)

    Kohler, Susanna

    2017-12-01

    Editors note:In these last two weeks of 2017, well be looking at a few selections that we havent yet discussed on AAS Nova from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume in January.Carbon Chain Anions and the Growth of Complex Organic Molecules in Titans IonospherePublished July2017Main takeaway:Graphic depicting some of the chemical reactions taking place in Titans atmosphere, leading to the generation of organic haze particles. [ESA]In a recently published study led by Ravi Desai (University College London), scientists used data from the Cassini mission to identify negatively charged molecules known as carbon chain anions in the atmosphere of Saturns largest moon, Titan.Why its interesting:Carbon chain anions are the building blocks ofmore complex molecules, and Titans thick nitrogen and methane atmosphere mightmimic the atmosphere of earlyEarth. This first unambiguous detection of carbon chain anions in a planet-like atmosphere might therefore teach us about the conditions and chemical reactions that eventually led to the development of life on Earth. And ifwe can use Titan to learn about how complex molecules grow from these anion chains, we may be able to identify auniversal pathway towards the ingredients for life.What weve learned so far:Cassini measured fewer and fewer lower-mass anions the deeper in Titans ionosphere that it looked and at the same time,an increase in the number of precursors to larger aerosol molecules further down. This tradeoff strongly suggests that the anions are indeed involved in building up the more complex molecules, seeding their eventual growth into the complex organic haze of Titans lower atmosphere.CitationR. T. Desai et al 2017 ApJL 844 L18. doi:10.3847/2041-8213/aa7851

  1. Preparation of lead titanate zirconate from metal citrates

    International Nuclear Information System (INIS)

    Bastos, C.M.R.

    1994-01-01

    Lead titanate zirconate (PZT) preparation from its metal constituent citrates have been investigated. Metal citrates were obtained by forced precipitation using a dehydration alcohol mixture. Salt solutions of lead nitrate and octahydrated zirconyl chloride, and titanium tetrachloride were treated separately with citric acid and ammonium hydroxide. Zirconium, titanium and lead oxides resulted from thermal decomposition of corresponding citrates at 500 0 C, 450 0 C and 250 0 C, respectively. Lead titanate (PT) and lead zirconate (P Z) were obtained by calcining at 450 0 C and 500 0 C, respectively, after adequate heating of citrates mechanically mixed in ethyl ether. PZT samples were obtained with different starting stoichiometry. Rhombohedral PZT-1 53/47 sample was prepared from co precipitating zirconyl ammonium and ammonium lead citrates in presence of ethanolic titanium oxide dispersion, and calcinating at 800 0 C. Rhombohedral PZT-q 52/48 sample was obtained from heating at 500 0 C for 2 hours a mixture of metal citrates coprecipitated by dehydration mixture of acetone-ethanol-formic acid (2:1:0,06). Tetragonal PZT-m stoichiometry 53/47 sample were obtained by calcining at after 600 0 C for 2 hours after heating a mechanically mixed metal citrates. PT phase arose at 400 0 C. PZT-m powders obtained in a range of 400 0 C-800 0 C were isostatically pressed, and sintered at 1100 0 C and 1200 0 C in saturated Pb O atmosphere. Rhombohedral sintered PZT was obtained with 7,78 g.cm -3 at 1200 0 C. (author). 123 refs, 53 figs, 32 tabs

  2. Bismuth iron oxide thin films using atomic layer deposition of alternating bismuth oxide and iron oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Puttaswamy, Manjunath; Vehkamäki, Marko [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Kukli, Kaupo, E-mail: kaupo.kukli@helsinki.fi [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); University of Tartu, Institute of Physics, W. Ostwald 1, EE-50411 Tartu (Estonia); Dimri, Mukesh Chandra [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Kemell, Marianna; Hatanpää, Timo; Heikkilä, Mikko J. [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Mizohata, Kenichiro [University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki (Finland); Stern, Raivo [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Ritala, Mikko; Leskelä, Markku [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland)

    2016-07-29

    Bismuth iron oxide films with varying contributions from Fe{sub 2}O{sub 3} or Bi{sub 2}O{sub 3} were prepared using atomic layer deposition. Bismuth (III) 2,3-dimethyl-2-butoxide, was used as the bismuth source, iron(III) tert-butoxide as the iron source and water vapor as the oxygen source. The films were deposited as stacks of alternate Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} layers. Films grown at 140 °C to the thickness of 200–220 nm were amorphous, but crystallized upon post-deposition annealing at 500 °C in nitrogen. Annealing of films with intermittent bismuth and iron oxide layers grown to different thicknesses influenced their surface morphology, crystal structure, composition, electrical and magnetic properties. Implications of multiferroic performance were recognized in the films with the remanent charge polarization varying from 1 to 5 μC/cm{sup 2} and magnetic coercivity varying from a few up to 8000 A/m. - Highlights: • Bismuth iron oxide thin films were grown by atomic layer deposition at 140 °C. • The major phase formed in the films upon annealing at 500 °C was BiFeO{sub 3}. • BiFeO{sub 3} films and films containing excess Bi favored electrical charge polarization. • Slight excess of iron oxide enhanced saturative magnetization behavior.

  3. Characterization of bismuth nanospheres deposited by plasma focus device

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, M., E-mail: cscientific2@aec.org.sy [IBA Laboratory, Chemistry Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Al-Hawat, Sh.; Akel, M. [Physics Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic); Mrad, O. [Chemistry Department, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus (Syrian Arab Republic)

    2015-02-14

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed.

  4. Inexpensive laser-induced surface modification in bismuth thin films

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, A. Reyes [Facultad de Ciencias, Universidad Autónoma del Estado de México, Carretera Toluca, Ixtlahuaca Kilómetro 15.5, C.P. 50200 Edo. de México (Mexico); Hautefeuille, M., E-mail: mathieu_h@ciencias.unam.mx [Facultad de Ciencias, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Circuito Exterior S/N, Coyoacán, Ciudad Universitaria, C.P. 04510 D.F. Mexico (Mexico); García, A. Esparza [Fotofísica y Películas Delgadas, Departamento de Tecnociencias, CCADET-UNAM, Circuito exterior s/n C.P. 04510 Cd. Universitaria, D.F. Mexico (Mexico); Mejia, O. Olea [Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco, Km 14.5, Unidad El Rosedal, 50200 San Cayetano, Estado de México (Mexico); López, M.A. Camacho [Facultad de Química, Universidad Autónoma del Estado de México, Tollocan s/n, esq. Paseo Colón, Toluca, Estado de México 50110 (Mexico)

    2015-05-01

    Highlights: • Laser-induced microbumps were formed on bismuth films using a simple, low-cost, laser setup. • The patterns, similar to those typically obtained with high-power lasers, were characterized. • Control of laser ablation conditions is critical in the fabrication of surface microbumps. - Abstract: In this work, we present results on texturing a 500 nm thick bismuth film, deposited by sputtering onto a glass slide using a low-cost homemade, near-infrared pulsed laser platform. A 785 nm laser diode of a CD–DVD pickup head was precisely focused on the sample mounted on a motorized two-axis translation stage to generate localized surface microbumps on the bismuth films. This simple method successfully transferred desired micropatterns on the films in a computer-numerical control fashion. Irradiated zones were characterized by atomic force microscopy and scanning electron microscopy. It was observed that final results are strongly dependent on irradiation parameters.

  5. Characterization of bismuth nanospheres deposited by plasma focus device

    International Nuclear Information System (INIS)

    Ahmad, M.; Al-Hawat, Sh.; Akel, M.; Mrad, O.

    2015-01-01

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed

  6. Spacecraft Exploration of Titan and Enceladus

    Science.gov (United States)

    Matson, D.; Coustenis, A.; Lunine, J. I.; Lebreton, J.; Reh, K.; Beauchamp, P.; Erd, C.

    2009-12-01

    The future exploration of Titan and Enceladus is very important for planetary science. The study titled Titan Saturn System Mission (TSSM) led to an announcement in which ESA and NASA prioritized future OPF missions, stating that TSSM is planned after EJSM (for details see http://www.lpi.usra.edu/opag/). The TSSM concept consists of an Orbiter that would carry two in situ elements: the Titan Montgolfiere hot air balloon and the Titan Lake Lander. This mission could launch in the 2023-2025 timeframe on a trajectory to arrive ~9 years later and begin a 4-year mission in the Saturnian system. At an appropriate time after arrival at Saturn, the montgolfiere would be delivered to Titan to begin its mission of airborne, scientific observations of Titan from an altitude of about 10 km above the surface. The montgolfiere would have a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) power system whose waste heat would warm the gas in the balloon, providing buoyancy. It would be designed to survive at least 6-12 months in Titan’s atmosphere. With the predicted winds and weather, it should be possible to circumnavigate the globe! Later, on a subsequent fly-by, the TSSM orbiter would send the Lake Lander to Titan. It would descend through the atmosphere making scientific measurements, much like Huygens did, and then land and float on one of Titan’s seas. This would be its oceanographic phase of making a physical and chemical assessment of the sea. The Lake Lander would operate for 8-10 hours until its batteries become depleted. Following the delivery of the in situ elements, the TSSM orbiter would then explore the Saturn system for two years on a tour that includes in situ sampling of Enceladus’ plumes as well as flybys of Titan. After the Saturn tour, the TSSM orbiter would go into orbit around Titan and carry out a global survey phase. Synergistic observations would be carried out by the TSSM orbiter and the in situ elements. The scientific requirements for

  7. Biomolecule-assisted hydrothermal synthesis of silver bismuth sulfide with nanostructures

    International Nuclear Information System (INIS)

    Kaowphong, Sulawan

    2012-01-01

    Silver bismuth sulfide (AgBiS 2 ) nanostructures were successfully prepared via a simple biomolecule-assisted hydrothermal synthesis at 200 °C for 12–72 h. Silver nitrate, bismuth nitrate and L-cysteine were used as starting materials. Here, the biomolecule, L-cysteine, was served as the sulfide source and a complexing agent. The products, characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were cubic AgBiS 2 nanoparticles with a diameter range of about 20–75 nm. It was found that their crystallinity and particle size increased with increasing reaction time. The energy dispersive X-ray spectroscopy (EDX) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses were used to confirm the stoichiometry of AgBiS 2 . The optical band gap of the AgBiS 2 nanoparticles, calculated from UV–vis spectra, was 3.0 eV which indicated a strong blue shift because of the quantum confinement effect. A possible formation mechanism of the AgBiS 2 nanoparticles was also discussed. - Graphical abstract: The optical band gap of the as-prepared AgBiS 2 nanoparticles displays a strong blue shift comparing to the 2.46 eV of bulk AgBiS 2 caused by the quantum confinement effects. Highlights: ► A simple biomolecule-assisted hydrothermal method is developed to prepare AgBiS 2 . ► L-Cysteine is served as the sulfide source and a complexing agent. ► Increase in band gap of the AgBiS 2 nanoparticles attributes to the quantum confinement effects.

  8. MES lead bismuth forced circulation loop and test results

    International Nuclear Information System (INIS)

    Ono, Mikinori; Mine, Tatsuya; Kitano, Teruaki; Kamata, Kin-ya

    2003-01-01

    Liquid lead-bismuth is a promising material as future reactor coolant or intensive neutron source material for accelerator driven system (ADS). Mitsui Engineering and Shipbuilding Co., Ltd. (MES) completed lead-bismuth coolant (LBC) forced circulation loop in May 2001 and acquired engineering data on economizer, electro magnetic pump, electro magnetic flow meter and so on. For quality control of LBC, oxygen sensor and filtering element are developing using some hydrogen and moisture mixed gases. Structural materials corrosion test for accelerator driver system (ADS) will start soon. And thermal hydraulic test for ADS will start in tree years. (author)

  9. Hydrolysis studies on bismuth nitrate: synthesis and crystallization of four novel polynuclear basic bismuth nitrates.

    Science.gov (United States)

    Miersch, L; Rüffer, T; Schlesinger, M; Lang, H; Mehring, M

    2012-09-03

    Hydrolysis of Bi(NO(3))(3) in aqueous solution gave crystals of the novel compounds [Bi(6)O(4)(OH)(4)(NO(3))(5)(H(2)O)](NO(3)) (1) and [Bi(6)O(4)(OH)(4)(NO(3))(6)(H(2)O)(2)]·H(2)O (2) among the series of hexanuclear bismuth oxido nitrates. Compounds 1 and 2 both crystallize in the monoclinic space group P2(1)/n but show significant differences in their lattice parameters: 1, a = 9.2516(6) Å, b = 13.4298(9) Å, c = 17.8471(14) Å, β = 94.531(6)°, V = 2210.5(3) Å(3); 2, a = 9.0149(3) Å, b = 16.9298(4) Å, c = 15.6864(4) Å, β = 90.129(3)°, V = 2394.06(12) Å(3). Variation of the conditions for partial hydrolysis of Bi(NO(3))(3) gave bismuth oxido nitrates of even higher nuclearity, [{Bi(38)O(45)(NO(3))(24)(DMSO)(26)}·4DMSO][{Bi(38)O(45)(NO(3))(24)(DMSO)(24)}·4DMSO] (3) and [{Bi(38)O(45)(NO(3))(24)(DMSO)(26)}·2DMSO][{Bi(38)O(45)(NO(3))(24)(DMSO)(24)}·0.5DMSO] (5), upon crystallization from DMSO. Bismuth oxido clusters 3 and 5 crystallize in the triclinic space group P1 both with two crystallographically independent molecules in the asymmetric unit. The following lattice parameters are observed: 3, a = 20.3804(10) Å, b = 20.3871(9) Å, c = 34.9715(15) Å, α = 76.657(4)°, β = 73.479(4)°, γ = 60.228(5)°, V = 12021.7(9) Å(3); 5, a = 20.0329(4) Å, b = 20.0601(4) Å, c = 34.3532(6) Å, α = 90.196(1)°, β = 91.344(2)°, γ = 119.370(2)°, V = 12025.8(4) Å(3). Differences in the number of DMSO molecules (coordinated and noncoordinated) and ligand (nitrate, DMSO) coordination modes are observed.

  10. Structural and dielectric characterization of praseodymium-modified lead titanate ceramics synthesized by the OPM route

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Alexandre H., E-mail: alehp1@yahoo.com.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos 13565-905, SP (Brazil); Souza, Flavio L., E-mail: fleandro.ufabc@gmail.com [Centro de Ciencias Naturais e Humanas, UFABC - Universidade Federal do ABC, Santo Andre 09210-170, SP (Brazil); Longo, Elson, E-mail: elson@iq.unesp.br [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP - Sao Paulo State University, Rua Francisco Degni, CP 355, Araraquara 14801-907, SP (Brazil); Leite, Edson R., E-mail: derl@power.ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos 13565-905, SP (Brazil); Camargo, Emerson R., E-mail: camargo@ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos 13565-905, SP (Brazil)

    2011-10-17

    Highlights: {yields} Highly reactive nanosized powders of Pb(0.8)Pr(0.2)TiO(3) were obtained by the OPM route. {yields} Tetragonal phase was observed by X-ray diffraction and confirmed by Raman spectroscopy. {yields} SEM images showed powders partially sintered with particles of approximately 54 nm. {yields} Dielectric measurements show a normal behavior for the ferroelectric to paraelectric transition. - Abstract: Quasi-spherical nanoparticles of praseodymium-modified lead titanate powder (Pb{sub 0.80}Pr{sub 0.20}TiO{sub 3}) with an average size of 54.8 nm were synthesized successfully by the oxidant-peroxo method (OPM) and were used to prepare highly dense ceramic bodies which were sintered at 1100 and 1150 deg. C for 2 h. A tetragonal phase was identified in the powder and ceramic samples by X-ray powder diffraction and FT-Raman spectroscopy at room temperature. The fractured surface of the ceramic sample showed a high degree of densification with fairly uniform grain sizes. Dielectric constants measured in the range of 30-300 deg. C at different frequencies (120 Hz and at 1, 10 and 100 kHz) indicated that samples with 20 mol% praseodymium showed normal ferroelectric behavior regardless of the sintering temperature.

  11. Structural and dielectric characterization of praseodymium-modified lead titanate ceramics synthesized by the OPM route

    International Nuclear Information System (INIS)

    Pinto, Alexandre H.; Souza, Flavio L.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

    2011-01-01

    Highlights: → Highly reactive nanosized powders of Pb(0.8)Pr(0.2)TiO(3) were obtained by the OPM route. → Tetragonal phase was observed by X-ray diffraction and confirmed by Raman spectroscopy. → SEM images showed powders partially sintered with particles of approximately 54 nm. → Dielectric measurements show a normal behavior for the ferroelectric to paraelectric transition. - Abstract: Quasi-spherical nanoparticles of praseodymium-modified lead titanate powder (Pb 0.80 Pr 0.20 TiO 3 ) with an average size of 54.8 nm were synthesized successfully by the oxidant-peroxo method (OPM) and were used to prepare highly dense ceramic bodies which were sintered at 1100 and 1150 deg. C for 2 h. A tetragonal phase was identified in the powder and ceramic samples by X-ray powder diffraction and FT-Raman spectroscopy at room temperature. The fractured surface of the ceramic sample showed a high degree of densification with fairly uniform grain sizes. Dielectric constants measured in the range of 30-300 deg. C at different frequencies (120 Hz and at 1, 10 and 100 kHz) indicated that samples with 20 mol% praseodymium showed normal ferroelectric behavior regardless of the sintering temperature.

  12. SAF line powder operations

    International Nuclear Information System (INIS)

    Frederickson, J.R.; Horgos, R.M.

    1983-10-01

    An automated nuclear fuel fabrication line is being designed for installation in the Fuels and Materials Examination Facility (FMEF) near Richland, Washington. The fabrication line will consist of seven major process systems: Receiving and Powder Preparation; Powder Conditioning; Pressing and Boat Loading; Debinding, Sintering, and Property Adjustment; Boat Transport; Pellet Inspection and Finishing; and Pin Operations. Fuel powder processing through pellet pressing will be discussed in this paper

  13. Two layer powder pressing

    International Nuclear Information System (INIS)

    Schreiner, H.

    1979-01-01

    First, significance and advantages of sintered materials consisting of two layers are pointed out. By means of the two layer powder pressing technique metal powders are formed resulting in compacts with high accuracy of shape and mass. Attributes of basic powders, different filling methods and pressing techniques are discussed. The described technique is supposed to find further applications in the field of two layer compacts in the near future

  14. Operation whey powder

    International Nuclear Information System (INIS)

    Brunner, E.

    1987-01-01

    The odyssey of the contaminated whey powder finally has come to an end, and the 5000 tonnes of whey now are designated for decontamination by means of an ion exchange technique. The article throws light upon the political and economic reasons that sent the whey powder off on a chaotic journey. It is worth mentioning in this context that the natural radioactivity of inorganic fertilizers is much higher than that of the whey powder in question. (HP) [de

  15. Bismuth oxyfluoride @ CMK-3 nanocomposite as cathode for lithium ion batteries

    Science.gov (United States)

    Ni, Dan; Sun, Wang; Xie, Liqiang; Fan, Qinghua; Wang, Zhenhua; Sun, Kening

    2018-01-01

    Bismuth oxyfluoride impregnated CMK-3 nanocomposite is synthesized by a facile nanocasting approach. Mesoporous carbon CMK-3 can suppress the aggregation and growth of bismuth oxyfluoride particles and offer rapid electron and Li ion passageways. Bismuth oxyfluoride nanoparticles are embedded in the mesoporous channels with particle size less than 20 nm. The bismuth oxyfluoride@CMK-3 nanocomposite maintains 148 mA h g-1 after 40 cycles with the capacity from both the bismuth oxyfluoride and the functional groups on the mesoporous carbon. The hybrid with confined bismuth oxyfluoride nanoparticles, conductive carbon network, and oxygen functional groups on the carbon matrix exhibits higher capacity and cycling stability than bulk bismuth oxyfluoride particles when used as lithium ion batteries cathode.

  16. Europium-doped calcium titanate: Optical and structural evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Mazzo, Tatiana Martelli; Pinatti, Ivo Mateus [INCTMN, LIEC, Departamento de Química, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, SP (Brazil); Macario, Leilane Roberta [INCTMN, LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14800-900 Araraquara, SP (Brazil); Avansi, Waldir [Centro de Ciências Exatas e de Tecnologia, Departamento de Física, Universidade Federal de São Carlos, Jardim Guanabara, 13565-905 São Carlos, SP (Brazil); Moreira, Mario Lucio [Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, Campus do Capão do Leão, 96001-970 Pelotas, RS (Brazil); Rosa, Ieda Lucia Viana, E-mail: ilvrosa@ufscar.br [INCTMN, LIEC, Departamento de Química, Universidade Federal de São Carlos, P.O. Box 676, 13565-905 São Carlos, SP (Brazil); Mastelaro, Valmor Roberto [Instituto de Física de São Carlos, Departamento de Física e Ciência dos Materiais, Universidade de São Paulo, P.O. Box 369, Av Trabalhador São Carlense 400, 13560-970 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN, LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14800-900 Araraquara, SP (Brazil)

    2014-02-05

    Highlights: • CaTiO{sub 3}:Eu{sup 3+} were obtained using low temperatures and very short reactional times. • The Eu{sup 3+} changes the local order–disorder of the [TiO{sub 6}] and [CaO{sub 12}] clusters. • Lifetime decay curves reveal two sites of symmetry of the Eu{sup 3+} in the CT matrix. • CaTiO{sub 3}:Eu{sup 3+} exhibit the strongest luminescent intensity and pure red color. -- Abstract: Pure Calcium Titanate (CT-pure) and Europium doped Calcium Titanate Ca{sub 1−x}Eu{sub x}TiO{sub 3} (x = 0.5%, 1.0% and 2.0% molar ratio of Eu{sup 3+} ions) powders were synthesized by hydrothermal microwave method (HTMW) at 140 °C for 8 min. The HTMW method appears to be an efficient method to prepare the luminescence materials using low temperatures and very short reactional times. In addition it is possible to determine specific correlations imposed by TiCl{sub 4} replacement by titanium isopropoxide [Ti(OC{sub 3}H{sub 7}){sub 4}] changing the reaction character and resulting in two different options of europium doping CT syntesis. To evaluate the influence of the structural order–disorder among the reactions and different properties of these materials, the following techniques were used for characterization. XANES spectroscopy that revealed that the introduction of Eu{sup 3+} ions into the CT lattice induces to significant changes in the local order–disorder around both, [TiO{sub 6}] and [CaO{sub 12}], complex clusters. PL spectra show Eu{sup 3+} emission lines ascribed to the Eu{sup 3+} transitions from {sup 5}D{sub 0} excited states to {sup 7}F{sub J} (J = 0, 1–4) fundamental states in CT:Eu{sup 3+} powders excited at 350 and 394 nm.

  17. Temperature gradient compatibility tests of some refractory metals and alloys in bismuth and bismuth--lithium solutions

    International Nuclear Information System (INIS)

    DiStefano, J.R.; Cavin, O.B.

    1976-11-01

    Quartz, T-111, and Mo thermal-convection loop tests were conducted at temperatures up to 700 0 C (100 0 C ΔT) to determine the compatibility of several refractory metals/alloys with bismuth and bismuth-lithium solutions for molten salt breeder reactor applications. Methods of evaluation included weight change measurements, metallographic examination, chemical and electron microprobe analysis, and mechanical properties tests. Molybdenum, T-111, and TA--10 percent W appear to be the most promising containment materials, while niobium and iron-based alloys are unacceptable

  18. Pharmaceutical powder compaction technology

    National Research Council Canada - National Science Library

    Çelik, Metin

    2011-01-01

    ... through the compaction formulation process and application. Compaction of powder constituents both active ingredient and excipients is examined to ensure consistent and reproducible disintegration and dispersion profiles...

  19. TITAN'S TRANSPORT-DRIVEN METHANE CYCLE

    International Nuclear Information System (INIS)

    Mitchell, Jonathan L.

    2012-01-01

    The mechanisms behind the occurrence of large cloud outbursts and precipitation on Titan have been disputed. A global- and annual-mean estimate of surface fluxes indicated only 1% of the insolation, or ∼0.04 W m –2 , is exchanged as sensible and/or latent fluxes. Since these fluxes are responsible for driving atmospheric convection, it has been argued that moist convection should be quite rare and precipitation even rarer, even if evaporation globally dominates the surface-atmosphere energy exchange. In contrast, climate simulations indicate substantial cloud formation and/or precipitation. We argue that the top-of-atmosphere (TOA) radiative imbalance is diagnostic of horizontal heat transport by Titan's atmosphere, and thus constrains the strength of the methane cycle. Simple calculations show the TOA radiative imbalance is ∼0.5-1 W m –2 in Titan's equatorial region, which implies 2-3 MW of latitudinal heat transport by the atmosphere. Our simulation of Titan's climate suggests this transport may occur primarily as latent heat, with net evaporation at the equator and net accumulation at higher latitudes. Thus, the methane cycle could be 10-20 times previous estimates. Opposing seasonal transport at solstices, compensation by sensible heat transport, and focusing of precipitation by large-scale dynamics could further enhance the local, instantaneous strength of Titan's methane cycle by a factor of several. A limited supply of surface liquids in regions of large surface radiative imbalance may throttle the methane cycle, and if so, we predict more frequent large storms over the lakes district during Titan's northern summer.

  20. Experimental simulations of ethylene evaporites on Titan

    Science.gov (United States)

    Czaplinski, E.; Farnsworth, K.; Singh, S.; Chevrier, V.

    2017-12-01

    Titan has an abundance of lakes and seas, as identified by the Cassini spacecraft. Major components of these liquid bodies include methane (CH4) and ethane (C2H6), however minor constituents are also thought to exist (e.g. ethylene (C2H4)). As the lakes and seas evaporate, 5-μm-bright deposits, resembling evaporite deposits on Earth, are left behind in a "bathtub ring" fashion. Previous studies include models of evaporites, and observations of the 5-μm-bright regions, but the community is still lacking a complete suite of experimental evaporite studies. In this study, we experimentally investigate evaporites in order to determine their composition and how they affect infrared spectra during the evaporation process. The University of Arkansas owns a specialized chamber that simulates the surface conditions of Titan ( 90 K and 1.5 bar). Gaseous hydrocarbons are condensed within the chamber and analyzed with Fourier Transform Infrared (FTIR) Spectroscopy and band depth calculations. In this study, three types of experiments were performed: ethane/ethylene, methane/ethylene, and methane/ethane/ethylene. For these experiments, methane was the only species that readily evaporated at Titan conditions (due to its high volatility), while ethane, being the more stable solvent, did not readily evaporate. Therefore, we will present spectral results of ethylene evaporite formation within these mixtures. Our results imply that evaporite formation is strongly dependent on the composition of the solvent. The north polar lakes of Titan are predicted to be methane-rich, indicating that they may be more likely to form evaporites. Alternatively, Ontario Lacus, a south polar lake, is predominately composed of ethane, which may make it more difficult to form evaporites. As we continue to study Titan's mysterious lakes and seas, we hope to draw insights on their exact composition, conditions for evaporite formation, habitability potential, and comparing Titan to prebiotic Earth.

  1. Volatile products controlling Titan's tholins production

    KAUST Repository

    Carrasco, Nathalie

    2012-05-01

    A quantitative agreement between nitrile relative abundances and Titan\\'s atmospheric composition was recently shown with a reactor simulating the global chemistry occurring in Titan\\'s atmosphere (Gautier et al. [2011]. Icarus, 213, 625-635). Here we present a complementary study on the same reactor using an in situ diagnostic of the gas phase composition. Various initial N 2/CH 4 gas mixtures (methane varying from 1% to 10%) are studied, with a monitoring of the methane consumption and of the stable gas neutrals by in situ mass spectrometry. Atomic hydrogen is also measured by optical emission spectroscopy. A positive correlation is found between atomic hydrogen abundance and the inhibition function for aerosol production. This confirms the suspected role of hydrogen as an inhibitor of heterogeneous organic growth processes, as found in Sciamma-O\\'Brien et al. (Sciamma-O\\'Brien et al. [2010]. Icarus, 209, 704-714). The study of the gas phase organic products is focussed on its evolution with the initial methane amount [CH 4] 0 and its comparison with the aerosol production efficiency. We identify a change in the stationary gas phase composition for intermediate methane amounts: below [CH 4] 0=5%, the gas phase composition is mainly dominated by nitrogen-containing species, whereas hydrocarbons are massively produced for [CH 4] 0>5%. This predominance of N-containing species at lower initial methane amount, compared with the maximum gas-to solid conversion observed in Sciamma-O\\'Brien et al. (2010) for identical methane amounts confirms the central role played by N-containing gas-phase compounds to produce tholins. Moreover, two protonated imines (methanimine CH 2NH and ethanamine CH 3CHNH) are detected in the ion composition in agreement with Titan\\'s INMS measurements, and reinforcing the suspected role of these chemical species on aerosol production. © 2012 Elsevier Inc.

  2. Predicting Passenger Survival Rates on the Titanic

    OpenAIRE

    Prateek Chanda

    2017-01-01

    The sinking of the RMS Titanic is one of the most infamous shipwrecks in history. On April 15, 1912, during her maiden voyage, the Titanic sank after colliding with an iceberg, killing 1502 out of 2224 passengers and crew. This sensational tragedy shocked the international community and led to better safety regulations for ships. One of the reasons that the shipwreck led to such loss of life was that there were not enough lifeboats for the passengers and crew. Although there was some el...

  3. Behavior under Extreme Conditions: The Titanic Disaster

    OpenAIRE

    Bruno S. Frey; David A. Savage; Benno Torgler

    2011-01-01

    During the night of April 14, 1912, the RMS Titanic collided with an iceberg on her maiden voyage. Two hours and 40 minutes later she sank, resulting in the loss of 1,501 lives—more than two-thirds of her 2,207 passengers and crew. This remains one of the deadliest peacetime maritime disasters in history and by far the most famous. For social scientists, evidence about how people behaved as the Titanic sunk offers a quasi-natural field experiment to explore behavior under extreme conditions o...

  4. Technological properties and structure of titanate melts

    International Nuclear Information System (INIS)

    Morozov, A.A.

    2002-01-01

    Power substantiation of existence of tough stream of complex anion ([TiO 6 ] 8- ) as a prevalent unit in titanate melts is given on the base of up-to-date knowledge about structure of metallurgical slags and results of investigations of thermophysical properties of these melts. It is shown that high crystallization ability of titanate melts at technological temperatures is determined by heterogeneity of liquid state - by presence up to 30 % of dispersed particles of solid phase solutions in matrix liquid [ru

  5. Printed Barium Strontium Titanate capacitors on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sette, Daniele [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg); Kovacova, Veronika [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Defay, Emmanuel, E-mail: emmanuel.defay@list.lu [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Luxembourg Institute of Science and Technology LIST, Materials Research and Technology Department, L-4422 Belvaux (Luxembourg)

    2015-08-31

    In this paper, we show that Barium Strontium Titanate (BST) films can be prepared by inkjet printing of sol–gel precursors on platinized silicon substrate. Moreover, a functional variable capacitor working in the GHz range has been made without any lithography or etching steps. Finally, this technology requires 40 times less precursors than the standard sol–gel spin-coating technique. - Highlights: • Inkjet printing of Barium Strontium Titanate films • Deposition on silicon substrate • Inkjet printed silver top electrode • First ever BST films thinner than 1 μm RF functional variable capacitor that has required no lithography.

  6. Biaxially textured articles formed by powder metallurgy

    Science.gov (United States)

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-08-05

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of ternary mixtures consisting of: Ni powder, Cu powder, and Al powder, Ni powder, Cr powder, and Al powder; Ni powder, W powder and Al powder; Ni powder, V powder, and Al powder; Ni powder, Mo powder, and Al powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} orientation texture; and further having a Curie temperature less than that of pure Ni.

  7. Measured and evaluated neutron cross sections of elemental bismuth

    International Nuclear Information System (INIS)

    Smith, A.; Guenther, P.; Smith, D.; Whalen, J.; Howerton, R.

    1980-04-01

    Neutron total cross sections of elemental bismuth are measured with broad resolution from 1.2 to 4.5 MeV to accuracies of approx. = 1%. Neutron-differential-elastic-scattering cross sections of bismuth are measured from 1.5 to 4.0 MeV at incident neutron energy intervals of approx.< 0.2 MeV over the scattered-neutron angular range approx. = 20 to 160 deg. Differential neutron cross sections for the excitation of observed states in bismuth at 895 +- 12, 1606 +- 14, 2590 +- 15, 2762 +- 29, 3022 +- 21, and 3144 +- 15 keV are determined at incident neutron energies up to 4.0 MeV. An optical-statistical model is deduced from the measured values. This model, the present experimental results, and information available elsewhere in the literature are used to construct a comprehensive evaluated nuclear data file for elemental bismuth in the ENDF format. The evaluated file is particularly suited to the neutronic needs of the fusion-fission hybrid designer. 87 references, 10 figures, 6 tables

  8. The reduction of background signal in bismuth germanate scintillators

    International Nuclear Information System (INIS)

    Lewis, T.A.

    1986-07-01

    Bismuth germanate (BGO) is one of several new scintillator materials developed in recent years. It has similar energy resolution (6-8%) to sodium iodide (NaI) but it is non-hygroscopic, has a much better Peak-to-Compton ratio and a stopping power about 2.3 times greater than NaI. For counting activated foils it represents an improvement on NaI for high efficiency counting where the resolution of a germanium spectrometer is not required. Two scintillators bought for this purpose were found to have a higher than expected background signal between 500 keV and 2 MeV which was traced to Bi207, an active isotope of bismuth with a 38 year half-life and not listed as occurring naturally. Reference to the manufacturer showed all crystals to be similarly contaminated. It is speculated that this active isotope arises from cosmic proton activation of associated lead in the ore from which the bismuth is extracted. Although not confirmed rigorously it has been shown that bismuth extracted from ore with a low lead content does not contain Bi207. Scintillators have been manufactured from uncontaminated material and reductions in the background signal of more than an order of magnitude have been achieved. This reduction will be of immediate benefit for monitoring nickel foils (fast flux monitors) activated in zero-energy reactors and should also permit the exploitation of other low probability reactions previously not thought to be feasible. (author)

  9. Short-term static corrosion tests in lead-bismuth

    Science.gov (United States)

    Soler Crespo, L.; Martín Muñoz, F. J.; Gómez Briceño, D.

    2001-07-01

    Martensitic steels have been proposed to be used as structural materials and as spallation target window in hybrid systems devoted to the transmutation of radioactive waste of long life and high activity. However, their compatibility with lead-bismuth in the operating conditions of these systems depends on the existence of a protective layer such as an oxide film. The feasibility of forming and maintaining an oxide layer or maintaining a pre-oxidised one has been studied. Martensitic steel F82Hmod. (8% Cr) has been tested in lead-bismuth under static and isothermal conditions at 400°C and 600°C. In order to study the first stages of the interaction between the steel and the eutectic, short-term tests (100 and 665 h) have been carried out. Pre-oxidised and as-received samples have been tested in atmospheres with different oxidant potential. For low oxygen concentration in lead-bismuth due to unexpected oxygen consumption in the experimental device, dissolution of as-received F82Hmod. occurs and pre-oxidation does not prevent the material dissolution. For high oxygen concentration, the pre-oxidation layer seems to improve the feasibility of protecting stainless steels controlling the oxygen potential of lead-bismuth with a gas phase.

  10. Short-term static corrosion tests in lead-bismuth

    International Nuclear Information System (INIS)

    Soler Crespo, L.; Martin Munoz, F.J.; Gomez Briceno, D.

    2001-01-01

    Martensitic steels have been proposed to be used as structural materials and as spallation target window in hybrid systems devoted to the transmutation of radioactive waste of long life and high activity. However, their compatibility with lead-bismuth in the operating conditions of these systems depends on the existence of a protective layer such as an oxide film. The feasibility of forming and maintaining an oxide layer or maintaining a pre-oxidised one has been studied. Martensitic steel F82Hmod. (8% Cr) has been tested in lead-bismuth under static and isothermal conditions at 400 o C and 600 o C. In order to study the first stages of the interaction between the steel and the eutectic, short-term tests (100 and 665 h) have been carried out. Pre-oxidised and as-received samples have been tested in atmospheres with different oxidant potential. For low oxygen concentration in lead-bismuth due to unexpected oxygen consumption in the experimental device, dissolution of as-received F82Hmod. occurs and pre-oxidation does not prevent the material dissolution. For high oxygen concentration, the pre-oxidation layer seems to improve the feasibility of protecting stainless steels controlling the oxygen potential of lead-bismuth with a gas phase

  11. Pairing from dynamically screened Coulomb repulsion in bismuth

    Science.gov (United States)

    Ruhman, Jonathan; Lee, Patrick A.

    2017-12-01

    Recently, Prakash et al. have discovered bulk superconductivity in single crystals of bismuth, which is a semimetal with extremely low carrier density. At such low density, we argue that conventional electron-phonon coupling is too weak to be responsible for the binding of electrons into Cooper pairs. We study a dynamically screened Coulomb interaction with effective attraction generated on the scale of the collective plasma modes. We model the electronic states in bismuth to include three Dirac pockets with high velocity and one hole pocket with a significantly smaller velocity. We find a weak-coupling instability, which is greatly enhanced by the presence of the hole pocket. Therefore we argue that bismuth is the first material to exhibit superconductivity driven by retardation effects of Coulomb repulsion alone. By using realistic parameters for bismuth we find that the acoustic plasma mode does not play the central role in pairing. We also discuss a matrix element effect, resulting from the Dirac nature of the conduction band, which may affect Tc in the s -wave channel without breaking time-reversal symmetry.

  12. Void worths in subcritical cores cooled by lead-bismuth

    International Nuclear Information System (INIS)

    Wallenius, Janne; Tucek, Kamil; Gudowski, Waclaw

    2001-01-01

    The introduction lead-bismuth coolant in accelerator driven transmutation systems (ADS) was: good neutron economy (higher source efficiency); natural circulation possible (decay heat removal); synergy with spallation target (simplified coolant management); high temperature of boiling (larger overpower margin); smaller void worths (operation at higher k-values). This paper deals with different aspects of the void worths in JAERI ADS

  13. Preparation of Ferroelectric Thin Films of Bismuth Layer Structured Compounds

    Science.gov (United States)

    Watanabe, Hitoshi; Mihara, Takashi; Yoshimori, Hiroyuki; Araujo, Carlos

    1995-09-01

    Ferroelectric thin films of bismuth layer structured compounds, SrBi2Ta2O9, SrBi2Nb2O9, SrBi4Ti4O15 and their solid solutions, were formed onto a sputtered platinum layer on a silicon substrate using spin-on technique and metal-organic decomposition (MOD) method. X-ray diffraction (XRD) analysis and some electrical measurements were performed on the prepared thin films. XRD results of SrBi2(Ta1- x, Nb x)2O9 films (0≤x≤1) showed that niobium ions substitute for tantalum ions in an arbitrary ratio without any change of the layer structure and lattice constants. Furthermore, XRD results of SrBi2 xTa2O9 films (0≤x≤1.5) indicated that the formation of the bismuth layer structure does not always require an accurate bismuth content. The layer structure was formed above 50% of the stoichiometric bismuth content in the general formula. SrBi2(Ta1- x, Nb x)2O9 films with various Ta/Nb ratios have large enough remanent polarization for nonvolatile memory application and have shown high fatigue resistance against 1011 cycles of full switching of the remanent polarization. Mixture films of the three compounds were also investigated.

  14. Ultrafast electron diffraction studies of optically excited thin bismuth films

    International Nuclear Information System (INIS)

    Rajkovic, Ivan

    2008-01-01

    This thesis contains work on the design and the realization of an experimental setup capable of providing sub-picosecond electron pulses for ultrafast electron diffraction experiments, and performing the study of ultrafast dynamics in bismuth after optical excitation using this setup. (orig.)

  15. Bismuth Ferrite for Active Control of Surface Plasmon Polariton Modes

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2014-01-01

    We propose and investigate several layouts of m etal-insulator-metal waveguide with active core which can be utilized for dynamic switching in photonic integrated circuits. The active material, bismuth ferrite (BiFeO3), is sandwiched between metal plates and changes i ts refractive index through...

  16. Ultrafast electron diffraction studies of optically excited thin bismuth films

    Energy Technology Data Exchange (ETDEWEB)

    Rajkovic, Ivan

    2008-10-21

    This thesis contains work on the design and the realization of an experimental setup capable of providing sub-picosecond electron pulses for ultrafast electron diffraction experiments, and performing the study of ultrafast dynamics in bismuth after optical excitation using this setup. (orig.)

  17. Phase transition of bismuth telluride thin films grown by MBE

    DEFF Research Database (Denmark)

    Fülöp, Attila; Song, Yuxin; Charpentier, Sophie

    2014-01-01

    A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formation...

  18. The Titan Sky Simulator ™ - Testing Prototype Balloons in Conditions Approximating those in Titan's Atmosphere

    Science.gov (United States)

    Nott, Julian

    This paper will describe practical work flying prototype balloons in the "The Titan Sky Simulator TM " in conditions approximating those found in Titan's atmosphere. Saturn's moon, Titan, is attracting intense scientific interest. This has led to wide interest in exploring it with Aerobots, balloons or airships. Their function would be similar to the Rovers exploring Mars, but instead of moving laboriously across the rough terrain on wheels, they would float freely from location to location. To design any balloon or airship it is essential to know the temperature of the lifting gas as this influences the volume of the gas, which in turn influences the lift. To determine this temperature it is necessary to know how heat is transferred between the craft and its surroundings. Heat transfer for existing balloons is well understood. However, Titan conditions are utterly different from those in which balloons have ever been flown, so heat transfer rates cannot currently be calculated. In particular, thermal radiation accounts for most heat transfer for existing balloons but over Titan heat transfer will be dominated by convection. To be able to make these fundamental calculations, it is necessary to get fundamental experimental data. This is being obtained by flying balloons in a Simulator filled with nitrogen gas at very low temperature, about 95° K / minus 180° C, typical of Titan's temperatures. Because the gas in the Simulator is so cold, operating at atmospheric pressure the density is close to that of Titan's atmosphere. "The Titan Sky Simulator TM " has an open interior approximately 4.5 meter tall and 2.5 meters square. It has already been operated at 95° K/-180° C. By the time of the Conference it is fully expected to have data to present from actual balloons flying at this temperature. Perhaps the most important purpose of this testing is to validate numerical [computational fluid dynamics] models being developed by Tim Colonius of Caltech. These numerical

  19. Sintered aluminium powders

    International Nuclear Information System (INIS)

    Stepanova, M.G.; Matveev, B.I.

    1974-01-01

    The mechanical and physical properties of aluminium powder alloys and the various methods employed to produce them are considered. Data are given on the hardening of the alloys SAP and SPAK-4, as well as the powder-alloy system Al-Cr-Zr. (L.M.)

  20. Investigation of Thermoelectric Parameters of Bi2Te3: TEGs Assembled using Pressure-Assisted Silver Powder Sintering-Based Joining Technology

    Science.gov (United States)

    Stranz, Andrej; Waag, Andreas; Peiner, Erwin

    2015-06-01

    Operation of thermoelectric generator (TEG) modules based on bismuth telluride alloys at temperatures higher than 250°C is mostly limited by the melting point of the assembly solder. Although the thermoelectric parameters of bismuth telluride materials degrade for temperatures >130°C, the power output of the module can be enhanced with an increase in the temperature difference. For this, a temperature-stable joining technique, especially for the hot side of the modules, is required. Fabrication and process parameters of TEG modules consisting of bismuth telluride legs, alumina ceramics and copper interconnects using a joining technique based on pressure-assisted silver powder sintering are described. Measurements of the thermal force, electrical resistance, and output power are presented that were performed for hot side module temperatures up to 350°C and temperature differences higher than 300°C. Temperature cycling and results measured during extended high-temperature operation are addressed.

  1. Efficient enhancement of bismuth NIR luminescence by aluminum and its mechanism in bismuth doped germanate laser glass

    DEFF Research Database (Denmark)

    Wang, L.P.; Tan, L.L.; Yue, Yuanzheng

    2016-01-01

    As a new member of laser glass family, bismuth-doped glasses have received rising interests due to the application of fiber amplifiers and laser sources in the new spectral range for the next-generation optical communication system. For practical application of the glasses, it must be considered ...

  2. Formation of gas-phase π-allyl radicals from propylene over bismuth oxide and γ-bismuth molybdate catalysts

    International Nuclear Information System (INIS)

    Martir, W.; Lunsford, J.H.

    1981-01-01

    Gas-phase π-allyl radicals were produced when propylene reacted over Bi 2 O 3 and γ-bismuth molybdate catalysts at 723 K. The pressure in the catalyst zone was varied between 5 x 10 -3 and 1 torr. The radicals were detected by EPR spectroscopy together with a matrix isolation technique in which argon was used as the diluent. The matrix was formed on a sapphire rod at 12 K which was located 33-cm downstream from the catalyst. Bismuth oxide was more effective in the production of gas-phase allyl radicals than γ-bismuth molybdate. By contrast α-bismuth molybdate was ineffective in forming allyl radicals and MoO 3 acted as a sink for radicals which were produced elsewhere in the system. Comparison of the π-allyl radical and the stable product concentrations over Bi 2 O 3 revealed that gas-phase radical recombination reactions served as a major pathway for the formation of 1,5-hexadiene. Addition of small amounts of gas-phase oxygen increased the concentration of allyl radicals, and at greater oxygen levels allyl peroxy radicals were detected. Because of the effect of temperature on the equilibrium between allyl and allyl peroxy radicals, the latter product must be formed in the cooler part of the system

  3. The Titan Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal; Jinschek, Jörg R.

    2009-01-01

    University of Denmark (DTU) provides a unique combination of techniques for studying materials of interest to the catalytic as well as the electronics and other communities [5]. DTU’s ETEM is based on the FEI Titan platform providing ultrahigh microscope stability pushing the imaging resolution into the sub...

  4. Infrared characterization of strontium titanate thin films

    International Nuclear Information System (INIS)

    Almeida, B.G.; Pietka, A.; Mendes, J.A.

    2004-01-01

    Strontium titanate thin films have been prepared at different oxygen pressures with various post-deposition annealing treatments. The films were deposited by pulsed laser ablation at room temperature on Si(0 0 1) substrates with a silica buffer layer. Infrared reflectance measurements were performed in order to determine relevant film parameters such as layer thicknesses and chemical composition. The infrared reflectance spectra were fitted by using adequate dielectric function forms for each layer. The fitting procedure provided the extraction of the dielectric functions of the strontium titanate film, the silica layer and the substrate. The as-deposited films are found to be amorphous, and their infrared spectra present peaks corresponding to modes with high damping constants. As the annealing time and temperature increases the strontium titanate layer becomes more ordered so that it can be described by its SrTiO 3 bulk mode parameters. Also, the silica layer grows along with the ordering of the strontium titanate film, due to oxidation during annealing

  5. The seasonal cycle of Titan's detached haze

    Science.gov (United States)

    West, Robert A.; Seignovert, Benoît; Rannou, Pascal; Dumont, Philip; Turtle, Elizabeth P.; Perry, Jason; Roy, Mou; Ovanessian, Aida

    2018-04-01

    Titan's `detached' haze, seen in Voyager images in 1980 and 1981 and monitored by the Cassini Imaging Science Subsystem (ISS) during the period 2004-2017, provides a measure of seasonal activity in Titan's mesosphere with observations over almost half of Saturn's seasonal cycle. Here we report on retrieved haze extinction profiles that reveal a depleted layer (having a diminished aerosol content), visually manifested as a gap between the main haze and a thin, detached upper layer. Our measurements show the disappearance of the feature in 2012 and its reappearance in 2016, as well as details after the reappearance. These observations highlight the dynamical nature of the detached haze. The reappearance seems congruent with earlier descriptions by climate models but more complex than previously described. It occurs in two steps, first as haze reappearing at 450 ± 20 km and one year later at 510 ± 20 km. These observations provide additional tight and valuable constraints about the underlying mechanisms, especially for Titan's mesosphere, that control Titan's haze cycle.

  6. An update of nitrile photochemistry on Titan

    Science.gov (United States)

    Yung, Yuk L.

    1987-01-01

    Comparisons are undertaken between laboratory kinetics experiments and Voyager observations in order to shed light on possible chemical reaction pathways to the generation of cyanogen and dicyanoacetylene in Titan's upper atmosphere. The predicted concentrations of the simple nitrile compounds are found to be of a magnitude realistically corresponding to the Voyager observations.

  7. TandEM: Titan and Enceladus mission

    Science.gov (United States)

    Coustenis, A.; Atreya, S.K.; Balint, T.; Brown, R.H.; Dougherty, M.K.; Ferri, F.; Fulchignoni, M.; Gautier, D.; Gowen, R.A.; Griffith, C.A.; Gurvits, L.I.; Jaumann, R.; Langevin, Y.; Leese, M.R.; Lunine, J.I.; McKay, C.P.; Moussas, X.; Muller-Wodarg, I.; Neubauer, F.; Owen, T.C.; Raulin, F.; Sittler, E.C.; Sohl, F.; Sotin, Christophe; Tobie, G.; Tokano, T.; Turtle, E.P.; Wahlund, J.-E.; Waite, J.H.; Baines, K.H.; Blamont, J.; Coates, A.J.; Dandouras, I.; Krimigis, T.; Lellouch, E.; Lorenz, R.D.; Morse, A.; Porco, C.C.; Hirtzig, M.; Saur, J.; Spilker, T.; Zarnecki, J.C.; Choi, E.; Achilleos, N.; Amils, R.; Annan, P.; Atkinson, D.H.; Benilan, Y.; Bertucci, C.; Bezard, B.; Bjoraker, G.L.; Blanc, M.; Boireau, L.; Bouman, J.; Cabane, M.; Capria, M.T.; Chassefiere, E.; Coll, P.; Combes, M.; Cooper, J.F.; Coradini, A.; Crary, F.; Cravens, T.; Daglis, I.A.; de Angelis, E.; De Bergh, C.; de Pater, I.; Dunford, C.; Durry, G.; Dutuit, O.; Fairbrother, D.; Flasar, F.M.; Fortes, A.D.; Frampton, R.; Fujimoto, M.; Galand, M.; Grasset, O.; Grott, M.; Haltigin, T.; Herique, A.; Hersant, F.; Hussmann, H.; Ip, W.; Johnson, R.; Kallio, E.; Kempf, S.; Knapmeyer, M.; Kofman, W.; Koop, R.; Kostiuk, T.; Krupp, N.; Kuppers, M.; Lammer, H.; Lara, L.-M.; Lavvas, P.; Le, Mouelic S.; Lebonnois, S.; Ledvina, S.; Li, Ji; Livengood, T.A.; Lopes, R.M.; Lopez-Moreno, J. -J.; Luz, D.; Mahaffy, P.R.; Mall, U.; Martinez-Frias, J.; Marty, B.; McCord, T.; Salvan, C.M.; Milillo, A.; Mitchell, D.G.; Modolo, R.; Mousis, O.; Nakamura, M.; Neish, Catherine D.; Nixon, C.A.; Mvondo, D.N.; Orton, G.; Paetzold, M.; Pitman, J.; Pogrebenko, S.; Pollard, W.; Prieto-Ballesteros, O.; Rannou, P.; Reh, K.; Richter, L.; Robb, F.T.; Rodrigo, R.; Rodriguez, S.; Romani, P.; Bermejo, M.R.; Sarris, E.T.; Schenk, P.; Schmitt, B.; Schmitz, N.; Schulze-Makuch, D.; Schwingenschuh, K.; Selig, A.; Sicardy, B.; Soderblom, L.; Spilker, L.J.; Stam, D.; Steele, A.; Stephan, K.; Strobel, D.F.; Szego, K.; Szopa,

    2009-01-01

    TandEM was proposed as an L-class (large) mission in response to ESA’s Cosmic Vision 2015–2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini–Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini–Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfière) and possibly several landing probes to be delivered through the atmosphere.

  8. Low-Latitude Ethane Rain on Titan

    Science.gov (United States)

    Dalba, Paul A.; Buratti, Bonnie J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-01-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years. These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally. Determining the composition of this rainfall is an important step in understanding the "methanological" cycle on Titan. I use data from Cassini VIMS to complete a spectroscopic investigation of multiple rain-wetted areas. I compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain. By comparing these spectral ratios to a model of liquid ethane, I find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. I show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, I show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form.

  9. Electrophoretic growth of lead zirconate titanate nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Limmer, S.J.; Seraji, S.; Forbess, M.J.; Wu Yun; Chou, T.P.; Nguyen, C.; Cao Guozhong [Washington Univ., Seattle, WA (United States). Dept. of Materials Science and Engineering

    2001-08-16

    Nanorods of lead zirconate titanate (PZT)-a ferro- and piezoelectric material-up to 10 {mu}m in length and 70 to 150 nm in diameter are produced by sol-gel electrophoresis of PZT in a track-etched polycarbonate membrane, which is used as a template. (orig.)

  10. Montgolfiere balloon missions from Mars and Titan

    Science.gov (United States)

    Jones, Jack A.

    2005-01-01

    Montgolfieres, which are balloons that are filled with heated ambient atmospheric gas, appear promising for the exploration of Mars as well as of Saturn's moon, Titan. On Earth, Montgolfieres are also known as 'hot air balloons'. Commercial versions are typically heated by burning propane, although a number of radiant and solar-heated Montgolfieres have been flown on earth by CNES.

  11. Impurities in barium titanate posistor ceramics

    Czech Academy of Sciences Publication Activity Database

    Korniyenko, S. M.; Bykov, I. P.; Glinchuk, M. J.; Laguta, V. V.; Belous, A. G.; Jastrabík, Lubomír

    2000-01-01

    Roč. 239, - (2000), s. 1209-1218 ISSN 0015-0193 Institutional research plan: CEZ:AV0Z1010914 Keywords : barium titanate phase transition * ESR * positive temperature coefficient of resistivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.547, year: 2000

  12. Radiation effects in uranium-niobium titanates

    International Nuclear Information System (INIS)

    Lian, J.; Wang, S.X.; Wang, L.M.; Ewing, R.C.

    2000-01-01

    Pyrochlore is an important actinide host phase proposed for the immobilization of high level nuclear wastes and excess weapon plutonium.[1] Synthetic pyrochlore has a great variety of chemical compositions due to the possibility of extensive substitutions in the pyrochlore structure.[2] During the synthesis of pyrochlore, additional complex titanate phases may form in small quantities. The response of these phases to radiation damage must be evaluated because volume expansion of minor phases may cause micro-fracturing. In this work, two complex uranium-niobium titanates, U 3 NbO 9.8 (U-rich titanate) and Nb 3 UO 10 (Nb-rich titanate) were synthesized by the alkoxide/nitrate route at 1300 deg. C under an argon atmosphere. The phase composition and structure were analyzed by EDS, BSE, XRD, EMPA and TEM techniques. An 800 KeVKr 2+ irradiation was performed using the IVEM-Tandem Facility at Argonne National Laboratory in a temperature range from 30 K to 973 K. The radiation effects were observed by in situ TEM

  13. Measurement of loose powder density

    International Nuclear Information System (INIS)

    Akhtar, S.; Ali, A.; Haider, A.; Farooque, M.

    2011-01-01

    Powder metallurgy is a conventional technique for making engineering articles from powders. Main objective is to produce final products with the highest possible uniform density, which depends on the initial loose powder characteristics. Producing, handling, characterizing and compacting materials in loose powder form are part of the manufacturing processes. Density of loose metallic or ceramic powder is an important parameter for die design. Loose powder density is required for calculating the exact mass of powder to fill the die cavity for producing intended green density of the powder compact. To fulfill this requirement of powder metallurgical processing, a loose powder density meter as per ASTM standards is designed and fabricated for measurement of density. The density of free flowing metallic powders can be determined using Hall flow meter funnel and density cup of 25 cm/sup 3/ volume. Density of metal powders like cobalt, manganese, spherical bronze and pure iron is measured and results are obtained with 99.9% accuracy. (author)

  14. Effects of prenatal exposure to surface-coated nanosized titanium dioxide (UV-Titan). A study in mice

    DEFF Research Database (Denmark)

    Hougaard, Karin S.; Jackson, Petra; Jensen, Keld A.

    2010-01-01

    to a nanoparticulate UV-filter (UV-titan L181). Methods: Time-mated mice (C57BL/6BomTac) were exposed by inhalation 1h/day to 42 mg/m(3) aerosolized powder (1.7.10(6) n/cm(3); peak-size: 97 nm) on gestation days 8-18. Endpoints included: maternal lung inflammation; gestational and litter parameters; offspring...... the central zone of the open field and exposed female offspring displayed enhanced prepulse inhibition. Cognitive function was unaffected (Morris water maze test). Conclusion: Inhalation exposure to nano-sized UV Titan dusts induced long term lung inflammation in time-mated adult female mice. Gestationally...

  15. Titan: a laboratory for prebiological organic chemistry

    Science.gov (United States)

    Sagan, C.; Thompson, W. R.; Khare, B. N.

    1992-01-01

    When we examine the atmospheres of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune), the satellites in the outer solar system, comets, and even--through microwave and infrared spectroscopy--the cold dilute gas and grains between the stars, we find a rich organic chemistry, presumably abiological, not only in most of the solar system but throughout the Milky Way galaxy. In part because the composition and surface pressure of the Earth's atmosphere 4 x 10(9) years ago are unknown, laboratory experiments on prebiological organic chemistry are at best suggestive; but we can test our understanding by looking more closely at the observed extraterrestrial organic chemistry. The present Account is restricted to atmospheric organic chemistry, primarily on the large moon of Saturn. Titan is a test of our understanding of the organic chemistry of planetary atmospheres. Its atmospheric bulk composition (N2/CH4) is intermediate between the highly reducing (H2/He/CH4/NH3/H2O) atmospheres of the Jovian planets and the more oxidized (N2/CO2/H2O) atmospheres of the terrestrial planets Mars and Venus. It has long been recognized that Titan's organic chemistry may have some relevance to the events that led to the origin of life on Earth. But with Titan surface temperatures approximately equal to 94 K and pressures approximately equal to 1.6 bar, the oceans of the early Earth have no ready analogue on Titan. Nevertheless, tectonic events in the water ice-rich interior or impact melting and slow re-freezing may lead to an episodic availability of liquid water. Indeed, the latter process is the equivalent of a approximately 10(3)-year-duration shallow aqueous sea over the entire surface of Titan.

  16. High energy storage density over a broad temperature range in sodium bismuth titanate-based lead-free ceramics.

    Science.gov (United States)

    Yang, Haibo; Yan, Fei; Lin, Ying; Wang, Tong; Wang, Fen

    2017-08-18

    A series of (1-x)Bi 0.48 La 0.02 Na 0.48 Li 0.02 Ti 0.98 Zr 0.02 O 3 -xNa 0.73 Bi 0.09 NbO 3 ((1-x)LLBNTZ-xNBN) (x = 0-0.14) ceramics were designed and fabricated using the conventional solid-state sintering method. The phase structure, microstructure, dielectric, ferroelectric and energy storage properties of the ceramics were systematically investigated. The results indicate that the addition of Na 0.73 Bi 0.09 NbO 3 (NBN) could decrease the remnant polarization (P r ) and improve the temperature stability of dielectric constant obviously. The working temperature range satisfying TCC 150  °C  ≤±15% of this work spans over 400 °C with the compositions of x ≥ 0.06. The maximum energy storage density can be obtained for the sample with x = 0.10 at room temperature, with an energy storage density of 2.04 J/cm 3 at 178 kV/cm. In addition, the (1-x)LLBNTZ-xNBN ceramics exhibit excellent energy storage properties over a wide temperature range from room temperature to 90 °C. The values of energy storage density and energy storage efficiency is 0.91 J/cm 3 and 79.51%, respectively, for the 0.90LLBNTZ-0.10NBN ceramic at the condition of 100 kV/cm and 90 °C. It can be concluded that the (1-x)LLBNTZ-xNBN ceramics are promising lead-free candidate materials for energy storage devices over a broad temperature range.

  17. Down-conversion luminescence and its temperature-sensing properties from Er3+-doped sodium bismuth titanate ferroelectric thin films

    Science.gov (United States)

    Wang, Shanshan; Zheng, Shanshan; Zhou, Hong; Pan, Anlian; Wu, Guangheng; Liu, Jun-ming

    2015-11-01

    Here, we demonstrate outstanding temperature-sensing properties from Na0.5Bi0.49Er0.01TiO3 (NBT:Er) thin films. The perovskite phase for them is stable in the temperature range from 80 to 440 K. Interestingly, the Er doping enhances the ferroelectric polarization and introduces local dipolar, which are positive for temperature sensing. Pumped by a 488-nm laser, the NBT:Er thin films show strong green luminescence with two bands around 525 and 548 nm. The intensity ratio I 525/ I 548 can be used for temperature sensing, and the maximum sensitivity is about 2.3 × 10-3 K-1, higher than that from Er-doped silicon oxide. These suggest NBT:Er thin film is a promising candidate for temperature sensor.

  18. Lead titanate nanotubes synthesized via ion-exchange method: Characteristics and formation mechanism

    International Nuclear Information System (INIS)

    Song Liang; Cao Lixin; Li Jingyu; Liu Wei; Zhang Fen; Zhu Lin; Su Ge

    2011-01-01

    Highlights: → Lead titanate nanotubes PbTi 3 O 7 were firstly synthesized by ion-exchange method. → Sodium titanate nanotubes have ion exchangeability. → Lead titanate nanotubes show a distinct red shift on absorption edge. - Abstract: A two-step method is presented for the synthesis of one dimensional lead titanate (PbTi 3 O 7 ) nanotubes. Firstly, titanate nanotubes were prepared by an alkaline hydrothermal process with TiO 2 nanopowder as precursor, and then lead titanate nanotubes were formed through an ion-exchange reaction. We found that sodium titanate nanotubes have ion exchangeability with lead ions, while protonated titanate nanotubes have not. For the first time, we distinguished the difference between sodium titanate nanotubes and protonated titanate nanotubes in the ion-exchange process, which reveals a layer space effect of nanotubes in the ion-exchange reaction. In comparison with sodium titanate, the synthesized lead titanate nanotubes show a narrowed bandgap.

  19. A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

    International Nuclear Information System (INIS)

    Ogawa, Makoto; Morita, Masashi; Igarashi, Shota; Sato, Soh

    2013-01-01

    A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst

  20. Equilibrium evaporation test of lead-bismuth eutectic and of tellurium in lead-bismuth

    International Nuclear Information System (INIS)

    Ohno, Shuji; Nishimura, Masahiro; Hamada, Hirotsugu; Miyahara, Shinya; Sasa, Toshinobu; Kurata, Yuji

    2005-01-01

    A series of equilibrium evaporation experiment was performed to acquire the essential and the fundamental knowledge about the transfer behavior of lead-bismuth eutectic (LBE) and impurity tellurium in LBE from liquid to gas phase. The experiments were conducted using the transpiration method in which saturated vapor in an isothermal evaporation pot was transported by inert carrier gas and collected outside of the pot. The size of the used evaporation pot is 8 cm inner diameter and 15 cm length. The weight of the LBE pool in the pot is about 500 g. The investigated temperature range was 450degC to 750degC. From this experiment and discussion using the data in literature, we have obtained several instructive and useful data on the LBE evaporation behavior such as saturated vapor pressure of LBE, vapor concentration of Pb, Bi and Bi 2 in LBE saturated gas phase, and activity coefficient of Pb in the LBE. The LBE vapor pressure equation is represented as the sum of Pb, Bi and Bi 2 vapor in the temperature range between 550degC and 750degC as logP[Pa]=10.2-10100/T[k]. The gas-liquid equilibrium partition coefficient of tellurium in LBE is in the range of 10 to 100, with no remarkable temperature dependency between 450degC and 750degC. This research was founded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT). (author)

  1. POWDER COAT APPLICATIONS

    Science.gov (United States)

    The report discusses an investigation of critical factors that affect the use of powder coatings on the environment, cost, quality, and production. The investigation involved a small business representative working with the National Defense Center for Environmental Excellence (ND...

  2. OIL SOLUTIONS POWDER

    Science.gov (United States)

    Technical product bulletin: aka OIL SOLUTIONS POWDER, SPILL GREEN LS, this miscellaneous oil spill control agent used in cleanups initially behaves like a synthetic sorbent, then as a solidifier as the molecular microencapsulating process occurs.

  3. Rapid semi-quantitative determination of bismuth in minerals using ascending paper chromatography (1961)

    International Nuclear Information System (INIS)

    Agrinier, H.

    1961-01-01

    The bismuth is separated by a solvent made up of acetone, water, and hydrofluoric and hydrochloric acids. The bismuth is developed with dimercapto-2.5 thio-diazole-1.3.4 and ammonium sulphide. The use of this method for the detection of bismuth in minerals makes it possible to determine the metal at a concentration of 5 x 10 -6 . (author) [fr

  4. Synthesis, processing behavior, and characterization of bismuth superconductors using freeze dried nitrate precursors

    International Nuclear Information System (INIS)

    Coppa, N.V.; Hults, W.L.; Smith, J.L.; Brynestad, J.

    1994-01-01

    The synthesis of Bi 2-x Pb x Sr 2 Ca 2 Cu 3 O 10 (Bi2223) powders from a freeze dried nitrate precursor is reported here. We examine the composition and morphology of the precursor material, describe the chemistry and kinetics of product formation, and evaluate the phase composition and superconducting properties of the products. A nitrate solution containing the appropriate ratio of cations was rapidly frozen and then freeze dried at low temperatures to form an atomic mixture of the component salts. The thermal processing of the freeze dried material consisted of three steps: (i) dehydration, (ii) denitration, and (iii) solid state reaction to form the Bi2223 superconducting product. Calcium substituted bismuthates and strontium-substituted calcium cuprate, not Bi2201, are the intermediates between the nitrates and the superconducting products. These highly disordered phases rapidly transform into Bi2212 or Bi2223 at higher temperatures (>790 degree C). The kinetics of product formation was studied using XRD analysis and magnetic susceptibility. The kinetics were shown to follow the nucleation and growth mechanism. Bi2223 formed after only 30 min at a few degrees below the melting point, and after 37 h Bi2223 products exhibited excellent phase composition and magnetic susceptibility characteristics

  5. New bismuth calcium oxysilicate with apatite structure: Synthesis and structural characterization

    International Nuclear Information System (INIS)

    Uvarov, Vladimir; Shenawi-Khalil, Sanaa; Popov, Inna

    2010-01-01

    New bismuth calcium silicon oxide Ca 4 Bi 4.3 (SiO 4 )(HSiO 4 ) 5 O 0.95 , with apatite structure has been synthesized. The structure was refined from powder X-ray diffraction data. The refinement revealed that the phase has P6 3 /m (176) space group with unit cell parameters a=b=9.6090(7) A, c=7.0521(7) A, V=563.9 A 3 and c/a=0.734. The R wp factor at Rietveld refinement was equal to 0.082. The synthesized phase has an unusual quantity of cation vacancies in a crystal lattice. Mechanisms of compensation of the excess charge of a lattice are considered and checked experimentally using the FT-IR spectroscopy, the thermal analysis and the XPS analysis. - Graphical abstract: The fragment Ca 4 Bi 4.3 (SiO 4 )(HSiO 4 ) 5 O 0.95 structure along c-axis in polygonal mode.

  6. Effect of reducing agent strength on the growth and thermoelectric performance of nanocrystalline bismuth telluride

    Science.gov (United States)

    Nour, Asmaa; Hassan, Nazly; Refaat, Heba M.; Soliman, Hesham M. A.; El-Dissouky, A.

    2018-03-01

    A novel combination of Trizma, as an environmentally friendly chelating agent, with either weak or strong reducing agent was used to produce n-type bismuth telluride (Bi2Te3) nanocrystals via water-based chemical route. The synthesized powders were consolidated into pellets utilizing spark plasma sintering (SPS). The sintered n-type pellets exhibited potentially high electrical conductivities (5.29 × 105 and 5.23 × 105 S.m‑1) and low lattice thermal conductivities (0.12 and 0.25 Wm‑1K‑1) respectively. These thermoelectric (TE) properties suggested that the partially coherent boundaries permitted significant phonons scattering and electrons transfer. These led to an enhanced figure-of-merit (ZT) values (0.52 and 0.97), which are considered to be significant among the reported ZT values at room-temperature for the undoped synthesized n-type Bi2Te3 nanoparticles. Therefore, the current investigation displayed an efficient method to improve ZT of TE materials via nanostructure orchestrating, resulting in a worthy candidate n-type nanostructured Bi2Te3 for room-temperature TE applications.

  7. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  8. Influence of bismuth on structural, elastic and spectroscopic properties of Nd{sup 3+} doped Zinc–Boro-Bismuthate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Gaurav; Sontakke, Atul D.; Karmakar, P.; Biswas, K.; Balaji, S.; Saha, R.; Sen, R.; Annapurna, K., E-mail: annapurnak@cgcri.res.in

    2014-05-01

    The present investigation reports, influence of bismuth addition on structural, elastic and spectral properties of [(99.5−x) {4ZnO−3B_2O_3}−0.5Nd{sub 2}O{sub 3}−x Bi{sub 2}O{sub 3} where x=0, 5, 10, 20, 30, 40, 50 and 60] glasses. The measured FTIR reflectance spectra facilitated a thorough insight of methodical modifications that are arising in the glass structure from borate (build by BO{sub 3} and BO{sub 4} units) to bismuthate (BiO{sub 3} and BiO{sub 6} units) network due to the increase of bismuth content ensuing with a steady decrease in host phonon energy (ν{sub ph}). The elastic properties estimated from measured longitudinal and shear ultrasonic velocities (U{sub L} and U{sub s}) demonstrated the reduction in network rigidity of glasses on Bi{sub 2}O{sub 3} inclusion. The three phenomenological Judd–Ofelt intensity parameters (Ω{sub 2,4,6}) were obtained from recorded absorption spectra of Nd{sup 3+} ions in these glasses and have been used to predict radiative properties as a function of variation in bismuth content. The reduced host phonon energy and high optical basicity effect due to Bi{sub 2}O{sub 3} incorporation remarkably improved the Nd{sup 3+} luminescence properties such as emission intensity, quantum yield and emission cross-section. The quantum yield showed a strong increase from mere 16% in Zinc–Borate glass to almost 73% in 60 mol% Bi{sub 2}O{sub 3} containing glass. Similarly, the emission cross-section for Nd{sup 3+4}F{sub 3/2}→{sup 4}I{sub 11/2} laser transition raised from 2.43×10{sup −20} cm{sup 2} to 3.95×10{sup −20} cm{sup 2} in studied concentration suggesting a strong improvement in Nd{sup 3+} laser spectroscopic properties in Zinc–Boro-Bismuthate glass. These materials may be promising for compact solid state infrared lasers. - Highlights: • Continuous structural changes associated with reduction in host phonon energy by Bi{sub 2}O{sub 3} inclusion. • Ultrasonic velocity study revealed reduced Debye

  9. Characterizing the Upper Atmosphere of Titan using the Titan Global Ionosphere- Thermosphere Model: Nitrogen and Methane.

    Science.gov (United States)

    Bell, J. M.; Waite, J. H.; Bar-Nun, A.; Bougher, S. W.; Ridley, A. J.; Magee, B.

    2008-12-01

    Recently, a great deal of effort has been put forth to explain the Cassini Ion-Neutral Mass Spectrometer (Waite et al [2004]) in-situ measurements of Titan's upper atmosphere (e.g. Muller-Wodarg [2008], Strobel [2008], Yelle et al [2008]). Currently, the community seems to agree that large amounts of CH4 are escaping from Titan's upper atmosphere at a rate of roughly 2.0 x 1027 molecules of CH4/s (3.33 x 1028 amu/s), representing a significant mass source to the Kronian Magnetosphere. However, such large escape fluxes from Titan are currently not corroborated by measurements onboard the Cassini Spacecraft. Thus, we posit another potential scenario: Aerosol depletion of atmospheric methane. Using the three-dimensional Titan Global Ionosphere-Thermosphere Model (T-GITM) (Bell et al [2008]), we explore the possible removal mechanisms of atmospheric gaseous constituents by these aerosols. Titan simulations are directly compared against Cassini Ion-Neutral Mass Spectrometer in-situ densities of N2 and CH4. From this work, we can then compare and contrast this aerosol depletion scenario against the currently posited hydrodynamic escape scenario, illustrating the merits and shortcomings of both.

  10. Characteristics of Inconel Powders for Powder-Bed Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Quy Bau Nguyen

    2017-10-01

    Full Text Available In this study, the flow characteristics and behaviors of virgin and recycled Inconel powder for powder-bed additive manufacturing (AM were studied using different powder characterization techniques. The results revealed that the particle size distribution (PSD for the selective laser melting (SLM process is typically in the range from 15 μm to 63 μm. The flow rate of virgin Inconel powder is around 28 s·(50 g−1. In addition, the packing density was found to be 60%. The rheological test results indicate that the virgin powder has reasonably good flowability compared with the recycled powder. The inter-relation between the powder characteristics is discussed herein. A propeller was successfully printed using the powder. The results suggest that Inconel powder is suitable for AM and can be a good reference for researchers who attempt to produce AM powders.

  11. Isotherms of ion exchange on titanates of alkaline metals

    International Nuclear Information System (INIS)

    Fillina, L.P.; Belinskaya, F.A.

    1986-01-01

    Present article is devoted to isotherms of ion exchange on titanates of alkaline metals. Therefore, finely dispersed hydrated titanates of alkaline metals (lithium, sodium, potassium) with ion exchange properties are obtained by means of alkaline hydrolysis of titanium chloride at high ph rates. Sorption of cations from salts solution of Li 2 SO 4 , NaNO 3 , Ca(NO 3 ) 2 , AgNO 3 by titanates is studied.

  12. Description of tritium release from lithium titanate at constant temperature

    Energy Technology Data Exchange (ETDEWEB)

    Pena, L; Lagos, S; Jimenez, J; Saravia, E [Comision Chilena de Energia Nuclear, Santiago (Chile)

    1998-03-01

    Lithium Titanate Ceramics have been prepared by the solid-state route, pebbles and pellets were fabricated by extrusion and their microstructure was characterized in our laboratories. The ceramic material was irradiated in the La Reina Reactor, RECH-1. A study of post-irradiation annealing test, was performed measuring Tritium release from the Lithium Titanate at constant temperature. The Bertone`s method modified by R. Verrall is used to determine the parameters of Tritium release from Lithium Titanate. (author)

  13. Phase transition of solid bismuth under high pressure

    International Nuclear Information System (INIS)

    Chen Hai-Yan; Xiang Shi-Kai; Yan Xiao-Zhen; Zhang Yi; Liu Sheng-Gang; Bi Yan; Zheng Li-Rong

    2016-01-01

    As a widely used pressure calibrator, the structural phase transitions of bismuth from phase I, to phase II, to phase III, and then to phase V with increasing pressure at 300 K have been widely confirmed. However, there are different structural versions for phase III, most of which are determined by x-ray diffraction (XRD) technology. Using x-ray absorption fine structure (XAFS) measurements combined with ab initio calculations, we show that the proposed incommensurate composite structure of bismuth of the three configurations is the best option. An abnormal continuous increase of the nearest-neighbor distance of phase III with elevated pressure is also observed. The electronic structure transformation from semimetal to metal is responsible for the complex behavior of structure transformation. (paper)

  14. Ac irreversibility line of bismuth-based high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Mehdaoui, A. [Laboratoire de Physique et de Spectroscopie Electronique, URA 1435 Faculte des Sciences, Universite de Haute Alsace 4, rue des Freres Lumiere, 68093 Mulhouse Cedex (France); Beille, J. [Laboratoire Louis Neel, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Berling, D.; Loegel, B. [Laboratoire de Physique et de Spectroscopie Electronique, URA 1435 Faculte des Sciences, Universite de Haute Alsace 4, rue des Freres Lumiere, 68093 Mulhouse Cedex (France); Noudem, J.G.; Tournier, R. [EPM-MATFORMAG, Laboratoire dElaboration par Procede Magnetique, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)

    1997-09-01

    We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe{lt}h{sub ac}{lt}100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL{close_quote}s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.{copyright} {ital 1997 Materials Research Society.}

  15. Ac irreversibility line of bismuth-based high temperature superconductors

    International Nuclear Information System (INIS)

    Mehdaoui, A.; Beille, J.; Berling, D.; Loegel, B.; Noudem, J.G.; Tournier, R.

    1997-01-01

    We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe ac <100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL close-quote s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.copyright 1997 Materials Research Society

  16. Quantum nernst effect in a bismuth single crystal

    International Nuclear Information System (INIS)

    Matsuo, M.; Endo, A.; Hatano, N.; Nakamura, H.; Shirasaki, R.; Sugihara, K.

    2009-07-01

    We calculate the phonon-drag contribution to the transverse (Nernst) thermoelectric power S yx in a bismuth single crystal subjected to a quantizing magnetic field. The calculated heights of the Nernst peaks originating from the hole Landau levels and their temperature dependence reproduce the right order of magnitude for those of the pronounced magneto-oscillations recently reported by Behnia et al. A striking experimental finding that S yx is much larger than the longitudinal (Seebeck) thermoelectric power S xx can be naturally explained as the effect of the phonon drag, combined with the well-known relation between the longitudinal and the Hall resistivity ρ xx >> |ρ yx | in a semi-metal bismuth. The calculation that includes the contribution of both holes and electrons suggests that some of the hitherto unexplained minor peaks located roughly at the fractional filling of the hole Landau levels are attributable to the electron Landau levels. (author)

  17. Nanophotonic Modulator with Bismuth Ferrite as Low-loss Switchable Material

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Lavrinenko, Andrei

    2015-01-01

    We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved.......We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved....

  18. Dose reduction using Bismuth protectors in chest computed tomography

    International Nuclear Information System (INIS)

    Anaya, R.

    2012-01-01

    This monography is about the Dose reduction using Bismuth protectors in chest CT. The radiation protection of specific areas is necessary when the tissues or radiosensitive organs are near the path of light beam. The correct use of protection represents a challenge for the radiologist because of the time and materials required. The method used was a prospective investigatio in CHPR (TC service) and the doses was measured with TLD dosimeters. It is important to use these protectors in children hospitals.

  19. Coupled atmosphere-ocean models of Titan's past

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, James B.; Lunine, Jonathan I.; Courtin, Regis

    1993-01-01

    The behavior and possible past evolution of fully coupled atmosphere and ocean model of Titan are investigated. It is found that Titan's surface temperature was about 20 K cooler at 4 Gyr ago and will be about 5 K warmer 0.5 Gyr in the future. The change in solar luminosity and the conversion of oceanic CH4 to C2H6 drive the evolution of the ocean and atmosphere over time. Titan appears to have experienced a frozen epoch about 3 Gyr ago independent of whether an ocean is present or not. This finding may have important implications for understanding the inventory of Titan's volatile compounds.

  20. History and challenges of barium titanate: Part I

    Directory of Open Access Journals (Sweden)

    Vijatović M.M.

    2008-01-01

    Full Text Available Barium titanate is the first ferroelectric ceramics and a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties. Barium titanate is a member of a large family of compounds with the general formula ABO3 called perovskites. Barium titanate can be prepared using different methods. The synthesis method depends on the desired characteristics for the end application. The used method has a significant influence on the structure and properties of barium titanate materials. In this review paper, Part I contains a study of the BaTiO3 structure and frequently used synthesis methods.

  1. Oxide layer stability in lead-bismuth at high temperature

    Science.gov (United States)

    Martín, F. J.; Soler, L.; Hernández, F.; Gómez-Briceño, D.

    2004-11-01

    Materials protection by 'in situ' oxidation has been studied in stagnant lead-bismuth, with different oxygen levels (H 2/H 2O ratios of 0.3 and 0.03), at temperatures from 535 °C to 600 °C and times from 100 to 3000 h. The materials tested were the martensitic steels F82Hmod, EM10 and T91 and the austenitic stainless steels, AISI 316L and AISI 304L. The results obtained point to the existence of an apparent threshold temperature above which corrosion occurs and the formation of a protective and stable oxide layer is not possible. This threshold temperature depends on material composition, oxygen concentration in the liquid lead-bismuth and time. The threshold temperature is higher for the austenitic steels, especially for the AISI 304L, and it increases with the oxygen concentration in the lead-bismuth. The oxide layer formed disappear with time and, after 3000 h all the materials, except AISI 304L, suffer corrosion, more severe for the martensitic steels and at the highest temperature tested.

  2. Theoretical study of bismuth-doped cadmium telluride

    Science.gov (United States)

    Menendez-Proupin, E.; Rios-Gonzalez, J. A.; Pena, J. L.

    Cadmium telluride heavily doped with bismuth has been proposed as an absorber with an intermediate band for solar cells. Increase in the photocurrent has been shown recently, although the overall cell efficiency has not improved. In this work, we study the electronic structure and the formation energies of the defects associated to bismuth impurities. We have performed electronic structure calculations within generalized density functional theory, using the exchange-correlation functional HSE(w) , where the range-separation parameter w has been tuned to reproduce the CdTe bandgap. Improving upon previous reports, we have included the spin-orbit interaction, which modifies the structure of the valence band and the energy levels of bismuth. We have found that interstitial Bi (Bii) tends to occupy Cd vacancies, cadmium substitution (BiCd) creates single donor level, while tellurium substitution (BiTe) is a shallow single acceptor. We investigate the interaction between these point defects and how can they be combined to create a partially filled intermediate band. Supported by FONDECYT Grant 1130437, CONACYT-SENER SUSTENTABILIDAD ENERGETICA/project CeMIE-Sol PY-207450/25 and PY-207450/26. JARG acknowledges CONACYT fellowship for research visit. Powered@NLHPC (ECM-02).

  3. Aerosol deposition of (Cu,Ti) substituted bismuth vanadate films

    Energy Technology Data Exchange (ETDEWEB)

    Exner, Jörg, E-mail: Functional.Materials@Uni-Bayreuth.de [University of Bayreuth, Department of Functional Materials, Universitätsstraße 30, 95440 Bayreuth (Germany); Fuierer, Paul [Materials and Metallurgical Engineering Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States); Moos, Ralf [University of Bayreuth, Department of Functional Materials, Universitätsstraße 30, 95440 Bayreuth (Germany)

    2014-12-31

    Bismuth vanadate, Bi{sub 4}V{sub 2}O{sub 11}, and related compounds with various metal (Me) substitutions, Bi{sub 4}(Me{sub x}V{sub 1−x}){sub 2}O{sub 11−δ}, show some of the highest ionic conductivities among the known solid oxide electrolytes. Films of Cu and Ti substituted bismuth vanadate were prepared by an aerosol deposition method, a spray coating process also described as room temperature impact consolidation. Resultant films, several microns in thickness, were dense with good adhesion to the substrate. Scanning electron microscopy and high temperature X-ray diffraction were used to monitor the effects of temperature on the structure and microstructure of the film. The particle size remained nano-scale while microstrain decreased rapidly up to 500 °C, above which coarsening and texturing increased rapidly. Impedance measurements of films deposited on inter-digital electrodes revealed an annealing effect on the ionic conductivity, with the conductivity exceeding that of a screen printed film, and approaching that of bulk ceramic. - Highlights: • Cu and Ti doped bismuth vanadate films were prepared by aerosol deposition (AD). • Dense 3–5 μm thick films were deposited on alumina, silicon and gold electrodes. • Annealing of the AD-layer increases the conductivity by 1.5 orders of magnitude. • Effect of temperature on structure and microstructure was investigated.

  4. Soluble Lead and Bismuth Chalcogenidometallates: Versatile Solders for Thermoelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao [Department; Son, Jae Sung [Department; School; Dolzhnikov, Dmitriy S. [Department; Filatov, Alexander S. [Department; Hazarika, Abhijit [Department; Wang, Yuanyuan [Department; Hudson, Margaret H. [Department; Sun, Cheng-Jun [Advanced; Chattopadhyay, Soma [Physical; Talapin, Dmitri V. [Department; Center

    2017-07-27

    Here we report the syntheses of largely unexplored lead and bismuth chalcogenidometallates in the solution phase. Using N2H4 as the solvent, new compounds such as K6Pb3Te6·7N2H4 were obtained. These soluble molecular compounds underwent cation exchange processes using resin chemistry, replacing Na+ or K+ by decomposable N2H5+ or tetraethylammonium cations. They also transformed into stoichiometric lead and bismuth chalcogenide nanomaterials with the addition of metal salts. Such a versatile chemistry led to a variety of composition-matched solders to join lead and bismuth chalcogenides and tune their charge transport properties at the grain boundaries. Solution-processed thin films composed of Bi0.5Sb1.5Te3 microparticles soldered by (N2H5)6Bi0.5Sb1.5Te6 exhibited thermoelectric power factors (~28 μW/cm K2) comparable to those in vacuum-deposited Bi0.5Sb1.5Te3 films. The soldering effect can also be integrated with attractive fabrication techniques for thermoelectric modules, such as screen printing, suggesting the potential of these solders in the rational design of printable and moldable thermoelectrics.

  5. Bismuth Oxysulfide and Its Polymer Nanocomposites for Efficient Purification

    Directory of Open Access Journals (Sweden)

    Yidong Luo

    2018-03-01

    Full Text Available The danger of toxic organic pollutants in both aquatic and air environments calls for high-efficiency purification material. Herein, layered bismuth copper oxychalcogenides, BiCuSO, nanosheets of high photocatalytic activity were introduced to the PVDF (Polyvinylidene Fluoride. The fibrous membranes provide an easy, efficient, and recyclable way to purify organic pollutant. The physical and photophysical properties of the BiCuSO and its polymer composite were characterized by scanning electron microscopy (SEM, X-ray diffraction (XRD, ultraviolet-visible diffuse reflection spectroscopy (DRS, X-ray photoelectron spectroscopy (XPS, electron spin resonance (EPR. Photocatalysis of Congo Red reveals that the BiCuSO/PVDF shows a superior photocatalytic activity of a 55% degradation rate in 70 min at visible light. The high photocatalytic activity is attributed to the exposed active {101} facets and the triple vacant associates V B i ‴ V O • • V B i ‴ . By engineering the intrinsic defects on the surface of bismuth oxysulfide, high solar-driven photocatalytic activity can be approached. The successful fabrication of the bismuth oxysulfide and its polymer nanocomposites provides an easy and general approach for high-performance purification materials for various applications.

  6. The thermal structure of Titan's atmosphere

    Science.gov (United States)

    Mckay, Christopher P.; Pollack, James B.; Courtin, Regis

    1989-01-01

    The present radiative-convective model of the Titan atmosphere thermal structure obtains the solar and IR radiation in a series of spectral intervals with vertical resolution. Haze properties have been determined with a microphysics model encompassing a minimum of free parameters. It is determined that gas and haze opacity alone, using temperatures established by Voyager observations, yields a model that is within a few percent of the radiative convective balance throughout the Titan atmosphere. Model calculations of the surface temperature are generally colder than the observed value by 5-10 K; better agreement is obtained through adjustment of the model parameters. Sunlight absorption by stratospheric haze and pressure-induced gas opacity in the IR are the most important thermal structure-controlling factors.

  7. Remember the Titans: A Theoretical Analysis

    Directory of Open Access Journals (Sweden)

    Rameca Leary

    2013-06-01

    Full Text Available This paper addresses a pivotal time in American history, when a 1971 Supreme Court mandate required southern school districts to end segregation (Daugherity, 2011. In Alexandria, Virginia, the merger of three rival high schools yielded a racially diverse football team and coaching staff. Beforehand, blacks and whites had their own schools. Many wondered how the new T.C. Williams Titans football team would fare. This paper takes an in-depth look at the film, Remember the Titans, which is based on this story. It analyzes the film using Gordon Allport’s (1954 Intergroup Contact Theory to assess how people from different backgrounds interact within group settings. It explores how communication barriers and the absence of knowledge can lead to ignorance. A 21st century legacy is also discussed, including ideas for further research. 

  8. Remember the Titans: A Theoretical Analysis

    Directory of Open Access Journals (Sweden)

    Rameca Leary

    2013-06-01

    Full Text Available This paper addresses a pivotal time in American history, when a 1971 Supreme Court mandate required southern school districts to end segregation (Daugherity, 2011. In Alexandria, Virginia, the merger of three rival high schools yielded a racially diverse football team and coaching staff. Beforehand, blacks and whites had their own schools. Many wondered how the new T.C. Williams Titans football team would fare. This paper takes an in-depth look at the film, Remember the Titans, which is based on this story. It analyzes the film using Gordon Allport’s (1954 Intergroup Contact Theory to assess how people from different backgrounds interact within group settings. It explores how communication barriers and the absence of knowledge can lead to ignorance. A 21st century legacy is also discussed, including ideas for further research.

  9. Heat capacity measurements on dysprosium titanate

    International Nuclear Information System (INIS)

    Kandan, R.; Prabhakara Reddy, B.; Panneerselvam, G.; Nagarajan, K.

    2014-01-01

    Dysprosium titanate is considered as a candidate material for use in the control rods of future nuclear reactors. The Dy 2 TiO 5 compound was prepared by solid-state synthesis and characterized by XRD technique. The high temperature enthalpy increments of dysprosium titanates have been measured for the first time by employing the method of inverse drop calorimetry in the temperature range 748-1645 K by using high temperature drop calorimeter. The calorimeter, the method of measurement and the procedure adopted for enthalpy increment measurements and analysis of the measured data to compute thermodynamic functions have been described elsewhere. The measured enthalpy increments were fitted to polynomial in temperature by using the least squares method. The fit equation in the temperature range from 298 to 1800 K is given

  10. Biaxially textured articles formed by powder metallurgy

    Science.gov (United States)

    Goyal, Amit; Williams, Robert K.; Kroeger, Donald M.

    2003-07-29

    A biaxially textured alloy article having a magnetism less than pure Ni includes a rolled and annealed compacted and sintered powder-metallurgy preform article, the preform article having been formed from a powder mixture selected from the group of mixtures consisting of: at least 60 at % Ni powder and at least one of Cr powder, W powder, V powder, Mo powder, Cu powder, Al powder, Ce powder, YSZ powder, Y powder, Mg powder, and RE powder; the article having a fine and homogeneous grain structure; and having a dominant cube oriented {100} orientation texture; and further having a Curie temperature less than that of pure Ni.

  11. Big Impacts and Transient Oceans on Titan

    Science.gov (United States)

    Zahnle, K. J.; Korycansky, D. G.; Nixon, C. A.

    2014-01-01

    We have studied the thermal consequences of very big impacts on Titan [1]. Titan's thick atmosphere and volatile-rich surface cause it to respond to big impacts in a somewhat Earth-like manner. Here we construct a simple globally-averaged model that tracks the flow of energy through the environment in the weeks, years, and millenia after a big comet strikes Titan. The model Titan is endowed with 1.4 bars of N2 and 0.07 bars of CH4, methane lakes, a water ice crust, and enough methane underground to saturate the regolith to the surface. We assume that half of the impact energy is immediately available to the atmosphere and surface while the other half is buried at the site of the crater and is unavailable on time scales of interest. The atmosphere and surface are treated as isothermal. We make the simplifying assumptions that the crust is everywhere as methane saturated as it was at the Huygens landing site, that the concentration of methane in the regolith is the same as it is at the surface, and that the crust is made of water ice. Heat flow into and out of the crust is approximated by step-functions. If the impact is great enough, ice melts. The meltwater oceans cool to the atmosphere conductively through an ice lid while at the base melting their way into the interior, driven down in part through Rayleigh-Taylor instabilities between the dense water and the warm ice. Topography, CO2, and hydrocarbons other than methane are ignored. Methane and ethane clathrate hydrates are discussed quantitatively but not fully incorporated into the model.

  12. The key to Mars, Titan and beyond?

    International Nuclear Information System (INIS)

    Zubrin, R.M.

    1990-01-01

    This paper discusses the use of nuclear rockets using indigenous Mars propellants for future missions to Mars and Titan, which would drastically reduce the mass and cost of the mission while increasing its capability. Special attention is given to the CO2-powered nuclear rocket using indigenous Martian fuel (NIMF) vehicle for hopping around on Mars. If water is available on Mars, it could make a NIMF propellant yielding an exhaust velocity of 3.4 km/sec, good enough to allow a piloted NIMF spacecraft to ascent from the surface of Mars and propel itself directly to LEO; if water is available on Phobos, a NIMF spacecraft could travel to earth orbit and then back to Phobos or Mars without any additional propellant from earth. One of the many exciting missions beyond Mars that will be made possible by NIMF technology is the exploration of Saturn's moon Titan. A small automated NIMF Titan explorer, with foldout wings and a NERVA (Nuclear Engine for Rocket Vehicle Applications) engine, is proposed

  13. Titanate nanotube coatings on biodegradable photopolymer scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Beke, S., E-mail: szabolcs.beke@iit.it [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Kőrösi, L. [Department of Biotechnology, Nanophage Therapy Center, Enviroinvest Corporation, Kertváros u. 2, H-7632, Pécs (Hungary); Scarpellini, A. [Department of Nanochemistry, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy); Anjum, F.; Brandi, F. [Department of Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova (Italy)

    2013-05-01

    Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion. Highlights: ► Biodegradable scaffolds were produced by mask-assisted UV laser photocuring. ► Titanate nanotube deposition was carried out without binding compounds or additives. ► The titanate nanotube coating can further improve the surface geometry of scaffolds. ► These reproducible platforms will be of high importance for biological applications.

  14. Modified titanate perovskites in photocatalytic water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Wlodarczak, M.; Ludwiczak, M.; Laniecki, M. [A. Mickiewicz Univ. (Poland)

    2010-07-01

    Received materials have structure of perovskite, what was shown by XRD diffraction patterns. Perovskite structure is present in all samples with strontium, barium and one sample with calcium. Moreover, received barium and strontium titanate are very similar to pattern materials. XRD results show, that temperature 500 C is too low to create perovskite structure in CaTiO{sub 3}. However, it is high enough in case of SrTiO{sub 3} and BaTiO{sub 3}. One regularity is obvious, surface area increases for samples calcined in lower temperature. There is a connection between surface area and dispersion of platinum. Both of them reach the greatest value to the calcium titanate. Catalytic activity was shown by all of received samples. Measurable values were received to samples calcined in 700 C. Calcium titanate had the best catalytic activity, both an amount of hydrogen and a ratio of hydrogen to platinum. There is one regularity to all samples, the ration of hydrogen to platinum increase when amount of platinum decrease. (orig.)

  15. Barium Titanate Nanoparticles for Biomarker Applications

    International Nuclear Information System (INIS)

    Matar, O; Hondow, N S; Brydson, R M D; Milne, S J; Brown, A P; Posada, O M; Wälti, C; Saunders, M; Murray, C A

    2015-01-01

    A tetragonal crystal structure is required for barium titanate nanoparticles to exhibit the nonlinear optical effect of second harmonic light generation (SHG) for use as a biomarker when illuminated by a near-infrared source. Here we use synchrotron XRD to elucidate the tetragonal phase of commercially purchased tetragonal, cubic and hydrothermally prepared barium titanate (BaTiO 3 ) nanoparticles by peak fitting with reference patterns. The local phase of individual nanoparticles is determined by STEM electron energy loss spectroscopy (EELS), measuring the core-loss O K-edge and the Ti L 3 -edge energy separation of the t 2g , e g peaks. The results show a change in energy separation between the t 2g and e g peak from the surface and core of the particles, suggesting an intraparticle phase mixture of the barium titanate nanoparticles. HAADF-STEM and bright field TEM-EDX show cellular uptake of the hydrothermally prepared BaTiO 3 nanoparticles, highlighting the potential for application as biomarkers. (paper)

  16. Large catchment area recharges Titan's Ontario Lacus

    Science.gov (United States)

    Dhingra, Rajani D.; Barnes, Jason W.; Yanites, Brian J.; Kirk, Randolph L.

    2018-01-01

    We seek to address the question of what processes are at work to fill Ontario Lacus while other, deeper south polar basins remain empty. Our hydrological analysis indicates that Ontario Lacus has a catchment area spanning 5.5% of Titan's surface and a large catchment area to lake surface area ratio. This large catchment area translates into large volumes of liquid making their way to Ontario Lacus after rainfall. The areal extent of the catchment extends to at least southern mid-latitudes (40°S). Mass conservation calculations indicate that runoff alone might completely fill Ontario Lacus within less than half a Titan year (1 Titan year = 29.5 Earth years) assuming no infiltration. Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of clouds over the southern mid and high-latitudes are consistent with precipitation feeding Ontario's large catchment area. This far-flung rain may be keeping Ontario Lacus filled, making it a liquid hydrocarbon oasis in the relatively dry south polar region.

  17. Titan through Time: Evolution of Titan's Atmosphere and its Hydrocarbon Cycle on the Surface

    Science.gov (United States)

    Gilliam, Ashley E.

    The Introduction and Appendix i-A outline briefly the history of Titan exploration since its discovery by Christiaan Huygens in 1675 through the recent International Mission of Cassini-Huygens.. Chapter 1: This chapter discusses two possible pathways of loss of the two main gases from Titan's post-accretional atmosphere, methane (CH 4) and ammonia (NH3), by the mechanisms of thermal escape and emission from the interior coupled with thermal escape. Chapter 2: In this chapter, a simple photolysis model is created, where the second most abundant component of the present-day Titan atmosphere, methane (CH4), can either escape the atmosphere or undergo photolytic conversion to ethane (C2H6). Chapter 3: This chapter examines different fluvial features on Titan, identified by the Cassini spacecraft, and evaluates the possibilities of channel formation by two mechanisms: dissolution of ice by a concentrated solution of ammonium sulfate, and by mechanical erosion by flow of liquid ammonia and liquid ethane. Chapter 4: This chapter presents: (1) new explicit mathematical solutions of mixed 1st and 2nd order chemical reactions, represented by ordinary differential first-degree and Riccati equations; (2) the computed present-day concentrations of the three gases in Titan's scale atmosphere, treated as at near-steady state; and (3) an analysis of the reported and computed atmospheric concentrations of CH4, CH 3, and C2H6 on Titan, based on the reaction rate parameters of the species, the rate parameters taken as constants representative of their mean values. Chapter 5: This chapter examines the possible reactions of methane formation in terms of the thermodynamic relationships of the reactions that include pure carbon as graphite, the gases H2, CO2, H2 O, and serpentinization and magnetite formation from olivine fayalite. (Abstract shortened by ProQuest.).

  18. Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance

    Science.gov (United States)

    Kattenhorn, Simon A.; Barnes, J. W.; McKay, C. P.; Lemke, L.; Beyer, R. A.; Radebaugh, J.; Adamkovics, M.; Atkinson, D. H.; Burr, D. M.; Colaprete, T.; Foch, R.; Le Mouélic, S.; Merrison, J.; Mitchell, J.; Rodriguez, S.; Schaller, E.

    2010-10-01

    Titan AVIATR - Aerial Vehicle for In Situ and Airborne Titan Reconnaissance - is a small (120 kg), nuclear-powered Titan airplane in the Discovery/New Frontiers class based on the concept of Lemke (2008 IPPW). The scientific goals of the mission are designed around the unique flexibility offered by an airborne platform: to explore Titan's diversity of surface landforms, processes, and compositions, as well as to study and measure the atmospheric circulation, aerosols, and humidity. AVIATR would address and surpass many of the science goals of hot-air balloons in Titan flagship studies. The strawman instrument payload is narrowly focused on the stated scientific objectives. The optical remote sensing suite comprises three instruments - an off-nadir high-resolution 2-micron camera, a horizon-looking 5-micron imager, and a 1-6 micron pushbroom near-infrared spectrometer. The in situ instruments include atmospheric structure, a methane humidity sensor, and a raindrop detector. An airplane has operational advantages over a balloon. Its piloted nature allows a go-to capability to image locations of interest in real time, thereby allowing for directed exploration of many features of primary geologic interest: Titan's sand dunes, mountains, craters, channels, and lakes. Subsequent imaging can capture changes in these features during the primary mission. AVIATR can fly predesigned routes, building up large context mosaics of areas of interest before swooping down to low altitude to acquire high-resolution images at 30-cm spatial sampling, similar to that of HiRISE at Mars. The elevation flexibility of the airplane allows us to acquire atmospheric profiles as a function of altitude at any desired location. Although limited by the direct-to-Earth downlink bandwidth, the total scientific data return from AVIATR will be >40 times that returned from Huygens. To maximize the science per bit, novel data storage and downlink techniques will be employed, including lossy compression

  19. AVIATR - Aerial Vehicle for In-situ and Airborne Titan Reconnaissance A Titan Airplane Mission Concept

    Science.gov (United States)

    Barnes, Jason W.; Lemke, Lawrence; Foch, Rick; McKay, Christopher P.; Beyer, Ross A.; Radebaugh, Jani; Atkinson, David H.; Lorenz, Ralph D.; LeMouelic, Stephane; Rodriguez, Sebastien; hide

    2011-01-01

    We describe a mission concept for a stand-alone Titan airplane mission: Aerial Vehicle for In-situ and Airborne Titan Reconnaissance (AVIATR). With independent delivery and direct-to-Earth communications, AVIATR could contribute to Titan science either alone or as part of a sustained Titan Exploration Program. As a focused mission, AVIATR as we have envisioned it would concentrate on the science that an airplane can do best: exploration of Titan's global diversity. We focus on surface geology/hydrology and lower-atmospheric structure and dynamics. With a carefully chosen set of seven instruments-2 near-IR cameras, 1 near-IR spectrometer, a RADAR altimeter, an atmospheric structure suite, a haze sensor, and a raindrop detector-AVIATR could accomplish a significant subset of the scientific objectives of the aerial element of flagship studies. The AVIATR spacecraft stack is composed of a Space Vehicle (SV) for cruise, an Entry Vehicle (EV) for entry and descent, and the Air Vehicle (AV) to fly in Titan's atmosphere. Using an Earth-Jupiter gravity assist trajectory delivers the spacecraft to Titan in 7.5 years, after which the AVIATR AV would operate for a 1-Earth-year nominal mission. We propose a novel 'gravity battery' climb-then-glide strategy to store energy for optimal use during telecommunications sessions. We would optimize our science by using the flexibility of the airplane platform, generating context data and stereo pairs by flying and banking the AV instead of using gimbaled cameras. AVIATR would climb up to 14 km altitude and descend down to 3.5 km altitude once per Earth day, allowing for repeated atmospheric structure and wind measurements all over the globe. An initial Team-X run at JPL priced the AVIATR mission at FY10 $715M based on the rules stipulated in the recent Discovery announcement of opportunity. Hence we find that a standalone Titan airplane mission can achieve important science building on Cassini's discoveries and can likely do so within

  20. Study on corrosion test techniques in lead bismuth eutectic flow. Joint research report in JFY2002

    International Nuclear Information System (INIS)

    Takahashi, Minoru; Sekimoto, Hiroshi

    2003-03-01

    The evaluation of corrosion behaviors of core and structural materials in lead bismuth eutectic is one of the key issues for the utilization of lead bismuth eutectic as a coolant of the primary loops of lead bismuth cooled fast breeder reactors (FBRs) and the intermediate heat transport media of new-type steam generators of the sodium cooled FBRs. The purpose of the present study is to establish corrosion test techniques in lead bismuth eutectic flow. The techniques of steel corrosion test and oxygen control in flowing lead bismuth eutectic, and the technologies of a lead bismuth flow test at high temperature and high velocity were developed through corrosion test using a lead bismuth flow test loop of the Tokyo Institute of Technology in JFY2002. The major results are summarized as follows: (1) Techniques of fabrication, mount and rinse of corrosion specimens, measurement method of weight loss, and SEM/EDX analysis method have been established through lead bismuth corrosion test. (2) Weight losses were measured, corrosion and lead bismuth-adhered layers and eroded parts were observed in two 1000 hr-corrosion tests, and the results were compared with each other for twelve existing steels including ODS, F82H and SUH-3. (3) An oxygen sensor made of zirconia electrolyte structurally resistant to thermal stress and thermal shock was developed and tested in the lead bismuth flow loop. Good performance has been obtained. (4) An oxygen control method by injecting argon and hydrogen mixture gas containing steam into lead bismuth was applied to the lead bismuth flow loop, and technical issues for the development of the oxygen control method were extracted. (5) Technical measures for freezing and leakage of lead bismuth in the flow loop were accumulated. (6) Technical measures for flow rate decrease/blockage due to precipitation of oxide and corrosion products in a low temperature section of the lead bismuth flow loop were accumulated. (7) Electromagnetic flow meters with MI

  1. Ultrafine hydrogen storage powders

    Science.gov (United States)

    Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

    2000-06-13

    A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

  2. Weighing fluidized powder

    International Nuclear Information System (INIS)

    Adomitis, J.T.; Larson, R.I.

    1980-01-01

    Fluidized powder is discharged from a fluidizing vessel into a container. Accurate metering is achieved by opening and closing the valve to discharge the powder in a series of short-duration periods until a predetermined weight is measured by a load cell. The duration of the discharge period may be increased in inverse proportion to the amount of powder in the vessel. Preferably the container is weighed between the discharge periods to prevent fluctuations resulting from dynamic effects. The gas discharged into the container causes the pressures in the vessel and container to equalize thereby decreasing the rate of discharge and increasing the accuracy of metering as the weight reaches the predetermined value. (author)

  3. Baking Powder Wars

    OpenAIRE

    Civitello, Linda

    2017-01-01

    How did a mid-nineteenth century American invention, baking powder, replace yeast as a leavening agent and create a culinary revolution as profound as the use of yeast thousands of years ago?The approach was two-pronged and gendered: business archives, U.S. government records and lawsuits revealed how baking powder was created, marketed, and regulated. Women’s diaries and cookbooks—personal, corporate, community, ethnic—from the eighteenth century to internet blogs showed the use women made o...

  4. A single drug for Helicobacter pylori infection: first results with a new bismuth triple monocapsule

    NARCIS (Netherlands)

    de Boer, W. A.; van Etten, R. J.; Schneeberger, P. M.; Tytgat, G. N.

    2000-01-01

    In this pilot study we investigated the efficacy and tolerability of a new monocapsule that contains a bismuth compound, tetracycline, and metronidazole. If proven to be effective, this monotherapy would turn the well-accepted multidrug regimen of standard bismuth-based triple therapy into an easy

  5. Method of Creating Micro-scale Silver Telluride Grains Covered with Bismuth Nanoparticles

    Science.gov (United States)

    Kim, Hyun-Jung (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor); Park, Yeonjoon (Inventor); Lee, Kunik (Inventor)

    2014-01-01

    Provided is a method of enhancing thermoelectric performance by surrounding crystalline semiconductors with nanoparticles by contacting a bismuth telluride material with a silver salt under a substantially inert atmosphere and a temperature approximately near the silver salt decomposition temperature; and recovering a metallic bismuth decorated material comprising silver telluride crystal grains.

  6. Build-up enhancement of photoluminescence from phenylazomethine bismuth dendrimer using Bi(OTf)3

    Science.gov (United States)

    Kambe, Tetsuya; Imaoka, Shotaro; Imaoka, Takane; Yamamoto, Kimihisa

    2018-05-01

    Metal assembly to a dendrimer can provide various functionalities based on the branched structure. Here, we researched assembly phenomena of bismuth salts in the phenylazomethine dendrimer and achieved enhancement of emission intensity per metal unit by using Bi(OTf)3. This enhancement suggested increasing of Bi-N coordination bonds derived from the bismuth units in the dendrimer.

  7. Selective oxidation of propylene to acrolein by silica-supported bismuth molybdate catalysts

    DEFF Research Database (Denmark)

    Duc, Duc Truong; Ha, Hanh Nguyen; Fehrmann, Rasmus

    2011-01-01

    Silica-supported bismuth molybdate catalysts have been prepared by impregnation, structurally characterized and examined as improved catalysts for the selective oxidation of propylene to acrolein. Catalysts with a wide range of loadings (from 10 to 90 wt%) of beta bismuth molybdate (β-Bi2Mo2O9) w...

  8. Screening of spontaneous polarization in lead titanate crystals

    International Nuclear Information System (INIS)

    Gavrilyachenko, V.G.; Semenchev, A.F.; Fesenko, E.G.

    1996-01-01

    Results of experimental investigations into electric conductivity of lead titanate crystals with different domain structure including single-domain are reported. The data obtained give grounds to believe that spontaneous titanate polarization is realized by the surface level and charge volumetric of free carriers and ionized impurity

  9. A Raman Study of Titanate Nanotubes | Liu | South African Journal ...

    African Journals Online (AJOL)

    The effect of the addition of NaOH or KOH on commercial Degussa Titania P25 was investigated using TEM, Raman and in situ Raman spectroscopy. Treatment of titania with conc. NaOH generated a tubular material corresponding to a sodium titanate. An in situ Raman study on the sodium titanate nanotubes as a function ...

  10. Reduced-graphene-oxide-and-strontium-titanate-based double

    Indian Academy of Sciences (India)

    Microwave-absorbing materials based on reduced graphene oxide (r-GO)/ strontium titanate were prepared by embedding in epoxy matrix. R-GO and strontium titanate were synthesized and characterized before composite fabrication. Microstructures of the constituent elements were studied by scanning electron ...

  11. Thermal conductivity reduction in oxygen-deficient strontium titanates

    NARCIS (Netherlands)

    Yu, Choongho; Scullin, Matthew L.; Huijben, Mark; Ramesh, Ramamoorthy; Majumdar, Arun

    2008-01-01

    We report significant thermal conductivity reduction in oxygen-deficient lanthanum-doped strontium titanate (Sr1−xLaxTiO3−δ) films as compared to unreduced strontium titanates. Our experimental results suggest that the oxygen vacancies could have played an important role in the reduction. This could

  12. Pressure slip casting and cold isostatic pressing of aluminum titanate green ceramics: A comparative evaluation

    Directory of Open Access Journals (Sweden)

    Ramanathan Papitha

    2013-12-01

    Full Text Available Aluminum titanate (Al2TiO5 green bodies were prepared from mixture of titania and alumina powders with different particle sizes by conventional slip casting (CSC, pressure slip casting (PSC and cold isostatic pressing (CIP. Precursor-powder mixtures were evaluated with respect to the powder properties, flow behaviours and shaping parameters. Green densities were measured and correlated with the fractographs. A substantial increase in green densities up to 60 %TD (theoretical density of 4.02 g/cm3, calculated based on rule of mixtures is observed with the application of 2–3 MPa pressure with PSC. While particle size distribution and solid loading are the most influential parameters in the case of CSC, with PSC pressure also plays a key role in achieving the higher green densities. Being a dry process, high pressure of > 100 MPa for CIP is essential to achieve densities in the range of 60–65 %TD. Slip pressurization under PSC conditions facilitate the rearrangement of particles through rolling, twisting and interlocking unlike CIP processing where pressure is needed to overcome the inter-particle friction.

  13. Synthesis of Barium Titanate from Titanyl Acylate Precursor by Sol-precipitate Method

    International Nuclear Information System (INIS)

    Thandar Win; Kyaw Naing; Khin Mar Tun

    2008-03-01

    Nanometersize barium titanates (BaTiO3:BT) powders can be obtained by sol-precipitate method in the presence of polyoxyethylene (20) sorbiton monooleate (Tween-80) as a polymeric surface modifier in a strong alkaline solution (pH > 13). FT-IR, TG/DTA, SEM and XRD were used to investigate the effects of the surfactant influence on the morphology of the obtained BaTiO3 powders. With adding surfactant, a slower rate of hydrolyzation is observed and the rate of condensation is slower. The addition of Tween-80 surfactant in general leads to the formation of smaller particle size of BaTi)3 (70-100 nm). Without adding surfactant, larger particle size of BaTiO3 (100-200 nm) was obtained. The nanometersize BaTiO3 powders were readily sintered at 1000-1200C. Raman-active modes of tetragonal phase BT were detected from Raman spectra of BaTiO3 between 800 0 C to 1200 0 C.

  14. Characterization and parametric study of mesoporous calcium titanate catalyst for transesterification of waste cooking oil into biodiesel

    International Nuclear Information System (INIS)

    Yahya, Noor Yahida; Ngadi, Norzita; Jusoh, Mazura; Halim, Noor Amirah Abdul

    2016-01-01

    Highlights: •Simple synthesis of mesoporous calcium titanate by sol-gel-hydrothermal method. •Improvement of characteristics and catalytic activity from commercial CaO. • Production of biodiesel at relatively mild reaction conditions. - Abstract: Mesoporous calcium titanate (MCT) catalyst was synthesized via a sol-gel-hydrothermal method and investigated as a catalyst for biodiesel production from waste cooking oil (WCO). Calcium was supported on titanate in order to increase their surface area, stability and consequently, improve its performance in the transesterification of WCO to biodiesel. Synthesized catalyst was characterized with powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), N_2 physisorption, Fourier transform-infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and carbon dioxide temperature-programmed desorption (CO_2-TPD). The catalyst possessed high surface area, basicity and stability than calcium oxide (CaO) catalyst. The highest biodiesel yield achieved was 80.0% in 3:1 of methanol to WCO molar ratio, 0.2 wt.% of MCT catalyst for 1 h at 65 °C. Reusability study suggested that this catalyst can be recycled for five successive runs.

  15. Formation of aluminum titanate with small additions of MgO and SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Guedes-Silva, Cecilia Chaves; Ferreira, Thiago dos Santos; Genova, Luis Antonio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carvalho, Flavio Machado de Souza, E-mail: cecilia.guedes@ipen.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Geociencias

    2016-03-15

    The formation of aluminum titanate was investigated by isothermal treatments of samples obtained from equimolar mixtures of alumina and titania, containing small amounts of silica and magnesia. Results of differential thermal analysis and Rietveld refinements of data collected by X-ray powder diffraction (XRPD) showed that additions of silica in amounts used in this work did not influence the formation of aluminum titanate. However, the presence of magnesia favored the formation of aluminum titanate in two steps, first one by incorporating Mg{sup 2+} into Al{sub 2}TiO{sub 5} lattice during its initial formation, and the second one by accelerating the Al{sub 2}TiO{sub 5} formation, contributing to large quantities of this phase. MgO doped samples have also developed a more suitable microstructure for stabilizing of Al{sub 2}TiO{sub 5}, what make them promising for applications such as thermal barriers, internal combustion engines and support material for catalyst. (author)

  16. Microwave hydrothermal synthesis and characterization of PZT 52/48 powders

    International Nuclear Information System (INIS)

    Teixeira, G.F.; Gasparotto, G.; Santos, N.A.; Zaghete, M.A.; Varela, J.A.; Longo, E.

    2009-01-01

    Full text: Lead Zirconate Titanate (PZT) is a ceramic witch has great interest because of their ferroelectric, piezoelectric, and other electrical properties. In this work Pb(ZrxTi1-x)O3 powders were synthesized by microwave hydrothermal synthesis (M-H) at 180°C without excess lead content. This method allows obtaining particles whit nanometer size, good stoichiometric controls, high purity and crystalline degree at low temperatures and short times of synthesis. Powders were synthesized with molar concentration of 0.15 mol.L -1 during different times: 30 min, 2, 4, 6 and 8 h. After that the powders were characterized by X-ray diffraction (XRD), Field Emission Gun (FEG) and photoluminescence (PL). Through analysis it is observed that the crystalline phase of PZT is obtained from 2 hours of synthesis and this same time also presents more intense PL emission. (author)

  17. NiTiO3 powders obtained by polymeric precursor method: Synthesis and characterization

    International Nuclear Information System (INIS)

    Lopes, K.P.; Cavalcante, L.S.; Simoes, A.Z.; Varela, J.A.; Longo, E.; Leite, E.R.

    2009-01-01

    Nickel titanate (NiTiO 3 ) powders were synthesized by the polymeric precursor method after thermal treatment at different temperatures for 2 h in air atmosphere. The decomposition of the precursors was monitored by differential scanning calorimetry and thermogravimetric analysis. The NiTiO 3 powders presented a reduction in the specific surface area and increase of the average particle size with the evolution of the temperature. The structural evolution of NiTiO 3 phase was accompanied by X-ray diffraction and Fourier transform Raman spectroscopy. By scanning electron microscopy was revealed the agglomerated nature of very fine particles of NiTiO 3 powders annealed from 600 to 1000 deg. C

  18. Maintenance procedures for the TITAN-I and TITAN-II reversed field pinch reactors

    International Nuclear Information System (INIS)

    Grotz, S.P.; Duggan, W.; Krakowski, R.; Najmabadi, F.; Wong, C.P.C.

    1989-01-01

    The TITAN reactor is a compact, high-power-density (neutron wall loading 18 MW/m 2 ) machine, based on the reversed-field-pinch (RFP) confinement concept. Two designs for the fusion power core have been examined: TITAN-I is based on a self-cooled lithium loop with a vanadium-alloy structure for the first wall, blanket and shield; and TITAN-II is based on an aqueous loop-in-pool design with a LiNO 3 solution as the coolant and breeder. The compact design of the TITAN fusion power core, (FPC) reduces the system to a few small and relatively low mass components, making toroidal segmentation of the FPC unnecessary. A single-piece maintenance procedure is possible. The potential advantages of single-piece maintenance procedures are: (1) Short period of down time; (2) improved reliability; (3) no adverse effects resulting from unequal levels of irradiation; and (4) ability to continually modify the FPC design. Increased availability can be expected from a fully pre-tested, single-piece FPC. Pre-testing of the FPC throughout the assembly process and prior to installation into the reactor vault is discussed. (orig.)

  19. Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating

    Czech Academy of Sciences Publication Activity Database

    Brunátová, T.; Matěj, Z.; Oleynikov, P.; Vesely, J.; Danis, S.; Popelková, Daniela; Kuzel, R.

    2014-01-01

    Roč. 98, December (2014), s. 26-36 ISSN 1044-5803 Institutional support: RVO:61389013 Keywords : titania nanowires * titanate nanorods * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.845, year: 2014

  20. Characterization of ceramic powder compacts

    International Nuclear Information System (INIS)

    Yanai, K.; Ishimoto, S.; Kubo, T.; Ito, K.; Ishikawa, T.; Hayashi, H.

    1995-01-01

    UO 2 and Al 2 O 3 powder packing structures in cylindrical powder compacts are observed by scanning electron microscopy using polished cross sections of compacts fixed by low viscosity epoxy resin. Hard aggregates which are not destroyed during powder compaction are observed in some of the UO 2 powder compacts. A technique to measure local density in powder compacts is developed based on counting characteristic X-ray intensity by energy dispersive X-ray analysis (EDX). The local density of the corner portion of the powder compact fabricated by double-acting dry press is higher than that of the inner portion. ((orig.))

  1. Localization and Related Phenomena in Multiply Connected Nanostructured Inverse Opal Bismuth

    Science.gov (United States)

    Bleiweiss, Michael; Saygi, Salih; Amirzadeh, Jafar; Datta, Timir; Lungu, Anca; Yin, Ming; Palm, Eric; Brandt, Bruce; Iqbal, Zafar

    2001-03-01

    The nanostructures were fabricated by pressure infiltration of bismuth into porous artificial opal and were characterized using SEM, EDX and XRD. These structures form a regular three-dimensional network in which the bismuth regions percolate in all directions between the close packed spheres of SiO_2. The sizes of the conducting regions are of the order of tens of nanometers. The static magnetic properties of both bismuth inverse opal and bulk bismuth were studied using a SQUID magnetometer. Transport measurements, including Hall, were done using standard ac four and six probe techniques in fields up to 17 T* and temperatures between 4.2 and 150 K. The results of these measurements, including the observation of localization phenomena, will be discussed. Comparisons will be made with published results on bismuth nanowires. *Performed at the National High Magnetic Field Lab (NHMFL) FSU, Tallahassee, FL. Partially supported by a grant from NASA.

  2. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, J.-C.; Kesler, V.G.; Troitskaia, I.B.

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr 2 Ti 2 O 7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr 2 Ti 2 O 7 have been determined as α Ti =872.8 and α O =1042.3 eV. Variations of cation–anion bond ionicity have been discussed using binding energy differences Δ Ti =(BE O 1s–BE Ti 2p 3/2 )=71.6 eV and Δ Pr =BE(Pr 3d 5/2 )−BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: ► Solid state synthesis of polar titanate Pr 2 Ti 2 O 7 . ► Structural and spectroscopic properties and electronic structure determination. ► Ti–O and Pr–O bonding analysis using Ti 2p 3/2 , Pr 3d 5/2 and O 1s core levels.

  3. A Moessbauer Spectral Study of the Hull Steel and Rusticles Recovered from the Titanic

    Energy Technology Data Exchange (ETDEWEB)

    Long, Gary J., E-mail: glong@umr.edu; Hautot, Dimitri [University of Missouri-Rolla, Department of Chemistry (United States); Grandjean, Fernande; Vandormael, D. [University of Liege, Institute of Physics, B5 (Belgium); Leighly, H. P. [University of Missouri-Rolla, Department of Metallurgical Engineering (United States)

    2004-09-15

    The recent recovery of steel from the Titanic has permitted a 295 K conversion electron Moessbauer spectral study of the Titanic hull plate steel oriented with the gamma-ray direction either perpendicular or parallel to the microstructural banding directions. The two spectra reveal virtually identical average orientations of the magnetization close to the plane of the plate. The hyperfine parameters are virtually identical to those of {alpha}-iron, a finding which agrees with the chemical analysis which reveals at most 0.21 wt% carbon corresponding to 3 wt% of cementite in pearlite. A 4.2 to 295 K transmission Moessbauer spectral study of the rusticles reveals small particles of geothite undergoing superparamagnetic relaxation with a blocking temperature of ca. 300 K. In addition approximately two percent of the Moessbauer spectral absorption area corresponds to a quadrupole doublet with hyperfine parameters typical of green rust. The identified iron containing components in therusticles agree with the powder X-ray diffraction results which reveal the predominant presence of small particles of poorly crystallized goethite and traces of quartz and green rust. An average size of 20{+-}5 nm for the goethite particles is obtained from both the average hyperfine field and the broadening of the X-ray diffraction peaks. The magnetic anisotropy constant of the goethite particles deduced from the hyperfine field and the particle size is 8x10{sup 3} J/m{sup 3}.

  4. Magnetically responsive enzyme powders

    Czech Academy of Sciences Publication Activity Database

    Pospišková, K.; Šafařík, Ivo

    2015-01-01

    Roč. 380, APR 2015 (2015), s. 197-200 ISSN 0304-8853 R&D Projects: GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : enzyme powders * cross-linking * magnetic modification * magnetic separation * magnetic iron oxides particles * microwave-assisted synthesis Subject RIV: CE - Biochemistry Impact factor: 2.357, year: 2015

  5. Powder neutron diffractometers

    International Nuclear Information System (INIS)

    Adib, M.

    2002-01-01

    Basic properties and applications of powder neutron Diffractometers are described for optimum use of the continuous neutron beams. These instruments are equipped with position sensitive detectors, neutron guide tubes, and both high intensity and high resolution modes of operation are possible .The principles of both direct and Fourier reverse time-of-flight neutron Diffractometers are also given

  6. Low Temperature Powder Coating

    Science.gov (United States)

    2011-02-09

    of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) • Legacy primers contain hexavalent chrome • Conventional powder coatings...coatings both in laboratory and field service evaluations • LTCPC allows environmental cost reductions through VOC/HAP elimination and hexavalent ... chrome reduction. • The LTCPC process greatly shortens the coating operation (LTCPC cures much more rapidly then conventional wet coatings) resulting in

  7. Laser cladding with powder

    NARCIS (Netherlands)

    Schneider, M.F.; Schneider, Marcel Fredrik

    1998-01-01

    This thesis is directed to laser cladding with powder and a CO2 laser as heat source. The laser beam intensity profile turned out to be an important pa6 Summary rameter in laser cladding. A numerical model was developed that allows the prediction of the surface temperature distribution that is

  8. Thermodynamics Calculation and Experimental Study on Separation of Bismuth from a Bismuth Glance Concentrate Through a Low-Temperature Molten Salt Smelting Process

    Science.gov (United States)

    Yang, Jian-Guang; He, De-Wen; Tang, Chao-Bo; Chen, Yong-Ming; Sun, Ya-Hui; Tang, Mo-Tang

    2011-08-01

    The main purpose of this study is to characterize and separate bismuth from a bismuth glance concentrate through a low-temperature, sulfur-fixing smelting process. This article reports on a study conducted on the optimization of process parameters, such as Na2CO3 and zinc oxide wt pct in charging, smelting temperature, smelting duration on the bismuth yield, resultant crude bismuth grade, and sulfur-fixing rate. A maximum bismuth recovery of 97.31 pct, crude bismuth grade of 96.93 pct, and 98.23 pct sulfur-fixing rate are obtained when a charge (containing 63.50 wt pct of Na2CO3 and 22.50 wt pct of bismuth glance, as well as 5 pct in excess of the stoichiometric requirement of zinc oxide dosage) is smelted at 1000 K (727 °C) for 150 minutes. This smelting operation is free from atmospheric pollution because zinc oxide is used as the sulfur-fixing agent, which can capture sulfur from bismuth sulfide and form the more thermodynamic-stable compound, zinc sulfide. The solid residue is subjected to a mineral dressing operation to obtain suspension, which is filtered to produce a cake, representing the solid particles of zinc sulfide. Based on the results of the chemical content analysis of the as-resultant zinc sulfide, more than 93 pct zinc sulfide can be recovered, and the recovered zinc sulfide grade can reach 60.20 pct. This material can be sold as zinc sulfide concentrate or roasted to be regenerated as zinc oxide.

  9. Ferroelectric relaxor behaviour and impedance spectroscopy of Bi{sub 2}O{sub 3}-doped barium zirconium titanate ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Mahajan, Sandeep; Thakur, O P; Bhattacharya, D K [Electroceramics Group, Solid State Physics Laboratory, Lucknow Road, Delhi-110054 (India); Sreenivas, K, E-mail: omprakasht@hotmail.co [Department of Physics and Astrophysics, University of Delhi- 110007 (India)

    2009-03-21

    Bi{sub 2}O{sub 3}-doped barium zirconate titanate ceramics, Ba{sub 1-x}Bi{sub x}(Zr{sub 0.05}Ti{sub 0.95})O{sub 3}, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi{sup 3+} substitutes A-site ion, and thereafter with higher Bi{sup 3+} content, it enters the B-site sub lattice. Substitution of Bi{sup 3+} ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300-723 K) and frequencies (40 Hz-1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a ceramic system, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.

  10. Bioavailability and chronic toxicity of bismuth citrate to earthworm Eisenia andrei exposed to natural sandy soil.

    Science.gov (United States)

    Omouri, Zohra; Hawari, Jalal; Fournier, Michel; Robidoux, Pierre Yves

    2018-01-01

    The present study describes bioavailability and chronic effects of bismuth to earthworms Eisenia andrei using OECD reproduction test. Adult earthworms were exposed to natural sandy soil contaminated artificially by bismuth citrate. Average total concentrations of bismuth in soil recovered by HNO 3 digestion ranged from 75 to 289mg/kg. Results indicate that bismuth decreased significantly all reproduction parameters of Eisenia andrei at concentrations ≥ 116mg/kg. However, number of hatched cocoons and number of juveniles seem to be more sensitive than total number of cocoons, as determined by IC 50 ; i.e., 182, 123 and > 289mg/kg, respectively. Bismuth did not affect Eisenia andrei growth and survival, and had little effect on phagocytic efficiency of coelomocytes. The low immunotoxicity effect might be explained by the involvement of other mechanisms i.e. bismuth sequestered by metal-binding compounds. After 28 days of exposure bismuth concentrations in earthworms tissue increased with increasing bismuth concentrations in soil reaching a stationary state of 21.37mg/kg dry tissue for 243mg Bi/kg dry soil total content. Data indicate also that after 56 days of incubation the average fractions of bismuth available extracted by KNO 3 aqueous solution in soil without earthworms varied from 0.0051 to 0.0229mg/kg, while in soil with earthworms bismuth concentration ranged between 0.310-1.347mg/kg dry soil. We presume that mucus and chelating agents produced by earthworms and by soil or/and earthworm gut microorganisms could explain this enhancement, as well as the role of dermal and ingestion routes of earthworms uptake to soil contaminant. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.; Troitskaia, I. B.

    2012-11-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr2Ti2O7 have been determined as αTi=872.8 and αO=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences ΔTi=(BE O 1s-BE Ti 2p3/2)=71.6 eV and ΔPr=BE(Pr 3d5/2)-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides.

  12. Radiophase development in hot-pressed alkoxide-derived titanate ceramics for nuclear waste stabilization

    International Nuclear Information System (INIS)

    Dickson, F.J.; Mitamura, H.; White, T.J.

    1989-01-01

    This paper reports phase development as a function of hot-pressing temperature studied in alkoxide-derived titanate-based ceramics doped with a 10 wt% loading of a sodium-rich (NAR) and a sodium-poor (NAP) simulated high-level waste. Pyrochlore was found to be the most abundant phase in both calcine powders. A pseudobrookite phase existed metastably at hot-pressing temperatures between 890 degrees and 920 degrees C. After hot-pressing at 1100 degrees C, the final phase assemblage for the NAP material consisted of zirconolite, hollandite-type, perovskite, alloy, and reduced rutile (Magneli phases). In addition, NAR samples contained hibonite, freudenbergite, and loveringite. Phase development was driven to completion over a very narrow temperature range (≤50 degrees C), beginning at 870 degrees and 850 degrees C for NAP and NAR, respectively, although full densification was not achieved below 1100 degrees C. Both waste forms exhibited comparable microstructure and aqueous durability

  13. Effect of mechanical milling on barium titanate (BaTiO3) perovskite

    Science.gov (United States)

    Singh, Rajan Kumar; Sanodia, Sagar; Jain, Neha; Kumar, Ranveer

    2018-05-01

    Commercial Barium Titanate BaTiO3 (BT) is milled by planetary ball mill in acetone medium using stainless steel bowl & ball for different hours. BT is an important perovskite oxide with structure ABO3. BT has applications in electro-optic devices, energy storing devices such as photovoltaic cells, thermistors, multiceramic capacitors & DRAMs etc. BT is non-toxic & environment friendly ceramic with high dielectric and piezoelectric property so it can be used as the substitute of PZT & PbTiO3. Here, we have investigated the effect of milling time and temperature on particle size and phase transition of BT powder. We used use Raman spectroscopy for studying the spectra of BT; XRD is used for structural study. Intensity (height) of Raman spectra and XRD spectra continuously decrease with increasing the milling hours and width if these spectra increases which indicates, decrease in BT size.

  14. Bismuth oxide nanotubes-graphene fiber-based flexible supercapacitors

    Science.gov (United States)

    Gopalsamy, Karthikeyan; Xu, Zhen; Zheng, Bingna; Huang, Tieqi; Kou, Liang; Zhao, Xiaoli; Gao, Chao

    2014-07-01

    Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics.Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics. Electronic supplementary information (ESI) available: Equations and characterization. SEM images of GGO, XRD and XPS of Bi2O3 NTs, HRTEM images and EDX Spectra of Bi2O3 NT5-GF, CV curves of Bi2O3NT5-GF, Bi2O3 NTs and bismuth nitrate in three-electrode system (vs. Ag/AgCl). CV and GCD curves of Bi2O3 NT1-GF and Bi2O3 NT3-GF. See DOI: 10.1039/c4nr02615b

  15. Conduction mechanism in bismuth silicate glasses containing titanium

    International Nuclear Information System (INIS)

    Dult, Meenakshi; Kundu, R.S.; Murugavel, S.; Punia, R.; Kishore, N.

    2014-01-01

    Bismuth silicate glasses mixed with different concentrations of titanium dioxide having compositions xTiO 2 –(60−x)Bi 2 O 3 –40SiO 2 with x=0, 5, 10, 15 and 20 were prepared by the normal melt quench technique. The frequency dependence of the ac electrical conductivity of different compositions of titanium bismuth silicate glasses has been studied in the frequency range 10 −1 Hz to 10 MHz and in the temperature range 623–703 K. The temperature and frequency dependent conductivity is found to obey Jonscher's universal power law for all the compositions of titanium bismuth silicate glass system. The dc conductivity (σ dc ), so called crossover frequency (ω H ), and frequency exponent (s) have been estimated from the fitting of experimental data of ac conductivity with Jonscher's universal power law. Enthalpy to dissociate the cation from its original site next to a charge compensating center (H f ) and enthalpy of migration (H m ) have also been estimated. The conductivity data have been analyzed in terms of different theoretical models to determine the possible conduction mechanism. Analysis of the conductivity data and the frequency exponent shows that the correlated barrier hopping of electrons between Ti 3+ and Ti 4+ ions in the glasses is the most favorable mechanism for ac conduction. The temperature dependent dc conductivity has been analyzed in the framework of theoretical variable range hopping model (VRH) proposed by Mott which describe the hopping conduction in disordered semiconducting systems. The various polaron hopping parameters have also been deduced. Mott's VRH model is found to be in good agreement with experimental data and the values of inverse localization length of s-like wave function (α) obtained by this model with modifications suggested by Punia et al. are close to the ones reported for a number of oxide glasses

  16. Methane, Ethane, and Nitrogen Stability on Titan

    Science.gov (United States)

    Hanley, J.; Grundy, W. M.; Thompson, G.; Dustrud, S.; Pearce, L.; Lindberg, G.; Roe, H. G.; Tegler, S.

    2017-12-01

    Many outer solar system bodies are likely to have a combination of methane, ethane and nitrogen. In particular the lakes of Titan are known to consist of these species. Understanding the past and current stability of these lakes requires characterizing the interactions of methane and ethane, along with nitrogen, as both liquids and ices. Our cryogenic laboratory setup allows us to explore ices down to 30 K through imaging, and transmission and Raman spectroscopy. Our recent work has shown that although methane and ethane have similar freezing points, when mixed they can remain liquid down to 72 K. Concurrently with the freezing point measurements we acquire transmission or Raman spectra of these mixtures to understand how the structural features change with concentration and temperature. Any mixing of these two species together will depress the freezing point of the lake below Titan's surface temperature, preventing them from freezing. We will present new results utilizing our recently acquired Raman spectrometer that allow us to explore both the liquid and solid phases of the ternary system of methane, ethane and nitrogen. In particular we will explore the effect of nitrogen on the eutectic of the methane-ethane system. At high pressure we find that the ternary creates two separate liquid phases. Through spectroscopy we determined the bottom layer to be nitrogen rich, and the top layer to be ethane rich. Identifying the eutectic, as well as understanding the liquidus and solidus points of combinations of these species, has implications for not only the lakes on the surface of Titan, but also for the evaporation/condensation/cloud cycle in the atmosphere, as well as the stability of these species on other outer solar system bodies. These results will help interpretation of future observational data, and guide current theoretical models.

  17. Composition And Geometry Of Titan'S Dunes

    Science.gov (United States)

    Le Gall, Alice; Janssen, M. A.; Wye, L. C.; Lorenz, R. D.; Radebaugh, J.; Cassini RADAR Team

    2009-09-01

    Fields of linear dunes cover a large portion of Titan's equatorial regions. As the Cassini mission continues, more of them are unveiled and examined by the microwave Titan RADAR Mapper both in the active and passive modes of operation of the instrument and with an increasing variety of observational geometries. In this presentation, we will show that the joint analysis of the SAR (Synthetic Aperture Radar) and radiometry observations of the dunes at closest approach supports the idea of different composition between the dunes and the interdunes. It suggests that the icy bedrock of Titan may be exposed, or partially exposed, in the interdunes. We also see regional differences among dune fields. Dunes are highly directional features; their visibility is controlled by the look direction and the incidence angle. We have developed a backscatter and emissivity model that takes into account the topography of the dunes relative to the geometry of observation as well as the composition of the dunes and interdunes. Compared to observations and, in particular, to multiple observations of areas at the overlap of several swaths, we argue the need for a diffuse scattering mechanism. The presence of ripples in the dunes and/or interdunes might account for the recorded backscatter. In this presentation we will also report the results of the T61 experiment. The T61 HiSAR sequence (on August 25, 2009) was designed to examine a small region of the Shangri-La dune field with a substantial sampling of incidence angles around the direction perpendicular to the dunes long axis. The spot in question was already observed during the T55 SAR swath and the T61 experiment should allow us to determine the slope of the dunes.

  18. Modeling the Chemical Complexity in Titan's Atmosphere

    Science.gov (United States)

    Vuitton, Veronique; Yelle, Roger; Klippenstein, Stephen J.; Horst, Sarah; Lavvas, Panayotis

    2018-06-01

    Titan's atmospheric chemistry is extremely complicated because of the multiplicity of chemical as well as physical processes involved. Chemical processes begin with the dissociation and ionization of the most abundant species, N2 and CH4, by a variety of energy sources, i.e. solar UV and X-ray photons, suprathermal electrons (reactions involving radicals as well as positive and negative ions, all possibly in some excited electronic and vibrational state. Heterogeneous chemistry at the surface of the aerosols could also play a significant role. The efficiency and outcome of these reactions depends strongly on the physical characteristics of the atmosphere, namely pressure and temperature, ranging from 1.5×103 to 10-10 mbar and from 70 to 200 K, respectively. Moreover, the distribution of the species is affected by molecular diffusion and winds as well as escape from the top of the atmosphere and condensation in the lower stratosphere.Photochemical and microphysical models are the keystones of our understanding of Titan's atmospheric chemistry. Their main objective is to compute the distribution and nature of minor chemical species (typically containing up to 6 carbon atoms) and haze particles, respectively. Density profiles are compared to the available observations, allowing to identify important processes and to highlight those that remain to be constrained in the laboratory, experimentally and/or theoretically. We argue that positive ion chemistry is at the origin of complex organic molecules, such as benzene, ammonia and hydrogen isocyanide while neutral-neutral radiative association reactions are a significant source of alkanes. We find that negatively charged macromolecules (m/z ~100) attract the abundant positive ions, which ultimately leads to the formation of the aerosols. We also discuss the possibility that an incoming flux of oxygen from Enceladus, another Saturn's satellite, is responsible for the presence of oxygen-bearing species in Titan's reductive

  19. Electronic properties of lithium titanate ceramic

    International Nuclear Information System (INIS)

    Padilla-Campos, Luis; Buljan, Antonio

    2001-01-01

    Research on tritium breeder material is fundamental to the development of deuterium-tritium type fusion reactors for producing clean, non contaminating, electrical energy, since only energy and helium, a harmless gas, are produced from the fusion reaction. Lithium titanate ceramic is one of the possible candidates for the tritium breeder material. This last material is thought to form part of the first wall of the nucleus of the reactor which will provide the necessary tritium for the fusion and will also serve as a shield. Lithium titanate has advantageous characteristics compared to other materials. Some of these are low activation under the irradiation of neutrons, good thermal stability, high density of lithium atoms and relatively fast tritium release at low temperatures. However, there are still several physical and chemical properties with respect to the tritium release mechanism and mechanical properties that have not been studied at all. This work presents a theoretical study of the electronic properties of lithium titanate ceramic and the corresponding tritiated material. Band calculations using the Extended H kel Tight-Binding approach were carried out. Results show that after substituting lithium for tritium atoms, the electronic states for the latter appear in the middle of prohibited band gap which it is an indication that the tritiated material should behave as a semiconductor, contrary to Li 2 TiO 3 which is a dielectric isolator. A study was also carried out to determine the energetically most favorable sites for the substitution of lithium for tritium atoms. Additionally, we analyzed possible pathways for the diffusion of a tritium atom within the crystalline structure of the Li 2 TiO 3

  20. Solution combustion synthesis and characterization of nanosized bismuth ferrite

    Science.gov (United States)

    Sai Kumar, V. Sesha; Rao, K. Venkateswara; Krishnaveni, T.; Kishore Goud, A. Shiva; Reddy, P. Ranjith

    2012-06-01

    The present paper describes a simple method of nanosized BiFeO3 by the solution combustion synthesis using bismuth and iron nitrates as oxidizers and the combination fuel of citric acid and ammonium hydroxide, with fuel to oxidizer ratio (Ψ = 1) one. The X-ray Diffraction results indicated rhombohedral phase (R3m) with JCPDS data card no: 72-2035. The ferroelectric transition of the sample at 8310C was detected by differential thermal analysis. Thermal analysis was done by Thermal gravimetric-Differential thermal analyzer and obtained results were presented in this paper.

  1. Phase 1 Final Report: Titan Submarine

    Science.gov (United States)

    Oleson, Steven R.; Lorenz, Ralph D.; Paul, Michael V.

    2015-01-01

    The conceptual design of a submarine for Saturn's moon Titan was a funded NASA Innovative Advanced Concepts (NIAC) Phase 1 for 2014. The proposal stated the desire to investigate what science a submarine for Titan's liquid hydrocarbon seas might accomplish and what that submarine might look like. Focusing on a flagship class science system (100 kg), it was found that a submersible platform can accomplish extensive science both above and below the surface of the Kraken Mare. Submerged science includes mapping using side-looking sonar, imaging and spectroscopy of the lake, as well as sampling of the lake's bottom and shallow shoreline. While surfaced, the submarine will not only sense weather conditions (including the interaction between the liquid and atmosphere) but also image the shoreline, as much as 2 km inland. This imaging requirement pushed the landing date to Titan's next summer period (2047) to allow for lighted conditions, as well as direct-to-Earth communication, avoiding the need for a separate relay orbiter spacecraft. Submerged and surfaced investigation are key to understanding both the hydrological cycle of Titan as well as gather hints to how life may have begun on Earth using liquid, sediment, and chemical interactions. An estimated 25 Mb of data per day would be generated by the various science packages. Most of the science packages (electronics at least) can be safely kept inside the submarine pressure vessel and warmed by the isotope power system.The baseline 90-day mission would be to sail submerged and surfaced around and through Kraken Mare investigating the shoreline and inlets to evaluate the sedimentary interaction both on the surface and then below. Depths of Kraken have yet to be sensed (Ligeia to the north is thought to be 200 m (656 ft) deep), but a maximum depth of 1,000 m (3,281 ft) for Kraken Mare was assumed for the design). The sub would spend 20 d at the interface between Kraken Mare and Ligeia Mare for clues to the drainage of

  2. Gamma Radiation Effect on Titan Yellow Solutions

    International Nuclear Information System (INIS)

    El-Banna, M.

    2012-01-01

    In the present work, the radiation induced color bleaching of Titan yellow dye (TY) in different solvents has been studied. The color bleaching of the dye solutions upon irradiation was followed spectrophotometrically. The % color bleaching of the dyes in different solvent systems was plotted against different gamma irradiation doses used and was determined and the obtained relationships were found to be linear in most cases. These relationships were used as calibration curves to determine the unknown irradiation dose. The results obtained were reproducible and showed differences from calculated values ranging from 10 % to 15 %

  3. FEI Titan 80-300 STEM

    Directory of Open Access Journals (Sweden)

    Marc Heggen

    2016-02-01

    Full Text Available The FEI Titan 80-300 STEM is a scanning transmission electron microscope equipped with a field emission electron gun, a three-condenser lens system, a monochromator unit, and a Cs probe corrector (CEOS, a post-column energy filter system (Gatan Tridiem 865 ER as well as a Gatan 2k slow scan CCD system. Characterised by a STEM resolution of 80 pm at 300 kV, the instrument was one of the first of a small number of sub-ångström resolution scanning transmission electron microscopes in the world when commissioned in 2006.

  4. Method to blend separator powders

    Science.gov (United States)

    Guidotti, Ronald A.; Andazola, Arthur H.; Reinhardt, Frederick W.

    2007-12-04

    A method for making a blended powder mixture, whereby two or more powders are mixed in a container with a liquid selected from nitrogen or short-chain alcohols, where at least one of the powders has an angle of repose greater than approximately 50 degrees. The method is useful in preparing blended powders of Li halides and MgO for use in the preparation of thermal battery separators.

  5. Plasma technology for powder particles

    Energy Technology Data Exchange (ETDEWEB)

    Kranz, E. (Technische Hochschule, Ilmenau (German Democratic Republic))

    1983-03-01

    A survey is given of principles and applications of plasma spraying and of powder transformation and generation in plasma considering spheroidization, grain size transformation, powder particle formation, powder reduction, and melting within the power range of 10/sup 3/ to 10/sup 7/ W. The products are applied in many industrial fields such as nuclear engineering, hard metal production, metallurgy, catalysis, and semiconductor techniques.

  6. Synthesis of Uranium nitride powders using metal uranium powders

    International Nuclear Information System (INIS)

    Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik

    2012-01-01

    Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N 15 gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work

  7. PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.

    2011-01-19

    Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), and measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.

  8. Investigation of corrosion, water reaction, polonium evaporation and bismuth resource in liquid metal lead-bismuth technology

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Hideki; Takizuka, Takakazu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kitano, Teruaki [Mitsui Shipbuilding and Engineering Co. Ltd., Tokyo (Japan)

    2000-10-01

    Lead-bismuth is the first candidate material for liquid metal target find coolant of fueled blanket system in accelerator-driven system (ADS) studied at JAERI. Advantages of the lead-bismuth utilization are non-active material, very low capture cross section, low melting point of 125degC and high boiling point of 1670degC, and beside coolant void reactivity become negative. But problems are due to the high corrosivity to most of the structural materials and the corrosive data are scarcity. In this report, corrosivity, reaction with water, thermal-hydraulics, chemical toxicity etc. are studied by investigating some facilities utilized and researched really for lead or lead-bismuth. And, furthermore, polonium evaporation rate and bismuth resource are investigated. Main results obtained are as follows: (1) In a refinery, there are enough employment experience for liquid Pb-Bi in period of about 17 years and not corrosion for the thermal conductive materials (1Cr-0.5Mo steel) used under the condition of natural convection with temperature around 400degC. (2) In Russia, extensive experience in the use as Russian submarines and in R and D during about 50 years are available. And as a result, it will be able to lead approximately zero corrosion for Cr-Si materials by adjusting oxygen film with oxygen concentration control between 10{sup -7} to 10{sup -5}% mass. However, the corrosion data are not enough systematically collected involving them in radiation dose field. (3) In liquid-dropping experiment, it is shown that interaction between water and high temperature liquid Pb-Bi is reduced steeply with rising of atmosphere pressure. But, in order to design the second circuit removal model of ADS, the interaction should be evaluated by water continuous injection experiment. (4) Polonium forms PbPo in Pb-Bi, and the evaporation rate become less three factor than that of Po, and furthermore, the rate decreases in the atmosphere. The effects of Po on employee and environment

  9. Titan and habitable planets around M-dwarfs.

    Science.gov (United States)

    Lunine, Jonathan I

    2010-01-01

    The Cassini-Huygens mission discovered an active "hydrologic cycle" on Saturn's giant moon Titan, in which methane takes the place of water. Shrouded by a dense nitrogen-methane atmosphere, Titan's surface is blanketed in the equatorial regions by dunes composed of solid organics, sculpted by wind and fluvial erosion, and dotted at the poles with lakes and seas of liquid methane and ethane. The underlying crust is almost certainly water ice, possibly in the form of gas hydrates (clathrate hydrates) dominated by methane as the included species. The processes that work the surface of Titan resemble in their overall balance no other moon in the solar system; instead, they are most like that of the Earth. The presence of methane in place of water, however, means that in any particular planetary system, a body like Titan will always be outside the orbit of an Earth-type planet. Around M-dwarfs, planets with a Titan-like climate will sit at 1 AU--a far more stable environment than the approximately 0.1 AU where Earth-like planets sit. However, an observable Titan-like exoplanet might have to be much larger than Titan itself to be observable, increasing the ratio of heat contributed to the surface atmosphere system from internal (geologic) processes versus photons from the parent star.

  10. Titan LEAF: A Sky Rover Granting Targeted Access to Titan's Lakes and Plains

    Science.gov (United States)

    Ross, Floyd; Lee, Greg; Sokol, Daniel; Goldman, Benjamin; Bolisay, Linden

    2016-10-01

    Northrop Grumman, in collaboration with L'Garde Inc. and Global Aerospace Corporation (GAC), has been developing the Titan Lifting Entry Atmospheric Flight (T-LEAF) sky rover to roam the atmosphere and observe at close quarters the lakes and plains of Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in situ instruments to the surface.T-LEAF is a maneuverable, buoyant air vehicle. Its aerodynamic shape provides its maneuverability, and its internal helium envelope reduces propulsion power requirements and also the risk of crashing. Because of these features, T-LEAF is not restricted to following prevailing wind patterns. This freedom of mobility allows it be commanded to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations.T-LEAF utilizes a variable power propulsion system, from high power at ~200W to low power at ~50W. High power mode uses the propellers and control surfaces for additional mobility and maneuverability. It also allows the vehicle to hover over specific locations for long duration surface observations. Low power mode utilizes GAC's Titan Winged Aerobot (TWA) concept, currently being developed with NASA funding, which achieves guided flight without the use of propellers or control surfaces. Although slower than high powered flight, this mode grants increased power to science instruments while still maintaining control over direction of travel.Additionally, T-LEAF is its own entry vehicle, with its leading edges protected by flexible thermal protection system (f-TPS) materials already being tested by NASA's Hypersonic Inflatable Aerodynamic Decelerator (HIAD) group. This f-TPS technology allows T-LEAF to inflate in space, like HIAD, and then enter the atmosphere fully deployed. This approach accommodates entry velocities from as low as ~1.8 km/s if entering from Titan orbit, up to ~6 km/s if entering directly from Saturn orbit, like the Huygens probe

  11. Storms in the tropics of Titan.

    Science.gov (United States)

    Schaller, E L; Roe, H G; Schneider, T; Brown, M E

    2009-08-13

    Methane clouds, lakes and most fluvial features on Saturn's moon Titan have been observed in the moist high latitudes, while the tropics have been nearly devoid of convective clouds and have shown an abundance of wind-carved surface features like dunes. The presence of small-scale channels and dry riverbeds near the equator observed by the Huygens probe at latitudes thought incapable of supporting convection (and thus strong rain) has been suggested to be due to geological seepage or other mechanisms not related to precipitation. Here we report the presence of bright, transient, tropospheric clouds in tropical latitudes. We find that the initial pulse of cloud activity generated planetary waves that instigated cloud activity at other latitudes across Titan that had been cloud-free for at least several years. These observations show that convective pulses at one latitude can trigger short-term convection at other latitudes, even those not generally considered capable of supporting convection, and may also explain the presence of methane-carved rivers and channels near the Huygens landing site.

  12. Big Bang Cosmic Titanic: Cause for Concern?

    Science.gov (United States)

    Gentry, Robert

    2013-04-01

    This abstract alerts physicists to a situation that, unless soon addressed, may yet affect PRL integrity. I refer to Stanley Brown's and DAE Robert Caldwell's rejection of PRL submission LJ12135, A Cosmic Titanic: Big Bang Cosmology Unravels Upon Discovery of Serious Flaws in Its Foundational Expansion Redshift Assumption, by their claim that BB is an established theory while ignoring our paper's Titanic, namely, that BB's foundational spacetime expansion redshifts assumption has now been proven to be irrefutably false because it is contradicted by our seminal discovery that GPS operation unequivocally proves that GR effects do not produce in-flight photon wavelength changes demanded by this central assumption. This discovery causes the big bang to collapse as quickly as did Ptolemaic cosmology when Copernicus discovered its foundational assumption was heliocentric, not geocentric. Additional evidence that something is amiss in PRL's treatment of LJ12135 comes from both Brown and EiC Gene Spouse agreeing to meet at my exhibit during last year's Atlanta APS to discuss this cover-up issue. Sprouse kept his commitment; Brown didn't. Question: If Brown could have refuted my claim of a cover-up, why didn't he come to present it before Gene Sprouse? I am appealing LJ12135's rejection.

  13. Ionization balance in Titan's nightside ionosphere

    Science.gov (United States)

    Vigren, E.; Galand, M.; Yelle, R. V.; Wellbrock, A.; Coates, A. J.; Snowden, D.; Cui, J.; Lavvas, P.; Edberg, N. J. T.; Shebanits, O.; Wahlund, J.-E.; Vuitton, V.; Mandt, K.

    2015-03-01

    Based on a multi-instrumental Cassini dataset we make model versus observation comparisons of plasma number densities, nP = (nenI)1/2 (ne and nI being the electron number density and total positive ion number density, respectively) and short-lived ion number densities (N+, CH2+, CH3+, CH4+) in the southern hemisphere of Titan's nightside ionosphere over altitudes ranging from 1100 and 1200 km and from 1100 to 1350 km, respectively. The nP model assumes photochemical equilibrium, ion-electron pair production driven by magnetospheric electron precipitation and dissociative recombination as the principal plasma neutralization process. The model to derive short-lived-ion number densities assumes photochemical equilibrium for the short-lived ions, primary ion production by electron-impact ionization of N2 and CH4 and removal of the short-lived ions through reactions with CH4. It is shown that the models reasonably reproduce the observations, both with regards to nP and the number densities of the short-lived ions. This is contrasted by the difficulties in accurately reproducing ion and electron number densities in Titan's sunlit ionosphere.

  14. Discovery of Temperate Latitude Clouds on Titan

    Science.gov (United States)

    Roe, H. G.; Bouchez, A. H.; Trujillo, C. A.; Schaller, E. L.; Brown, M. E.

    2005-01-01

    Until now, all the clouds imaged in Titan's troposphere have been found at far southern latitudes (60°-90° south). The occurrence and location of these clouds is thought to be the result of convection driven by the maximum annual solar heating of Titan's surface, which occurs at summer solstice (2002 October) in this south polar region. We report the first observations of a new recurring type of tropospheric cloud feature, confined narrowly to ~40° south latitude, which cannot be explained by this simple insolation hypothesis. We propose two classes of formation scenario, one linked to surface geography and the other to seasonally evolving circulation, which will be easily distinguished with continued observations over the next few years. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (US), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil), and CONICET (Argentina).

  15. Titan Coupled Surface/Atmosphere Retrievals

    Science.gov (United States)

    West, R. A.; Pitman, K. M.

    2009-05-01

    Titan's thick haze obscures its surface at visible wavelengths and hinders surface photometric studies in the near-infrared. The large vertical extent of the haze produces two effects which require radiative transfer analysis beyond the capability of plane-parallel multi-scatter models. Haze aerosols extend to altitudes above 500 km and require a spherical-shell RT algorithm close to the limb or terminator. Even near nadir viewing, horizontal scattering at spatial scales less than a few hundred km requires a code capable of simulating the adjacency effect. The adjacency effect will reduce contrast more for small spatial scales than for large spatial scales, and the amount of contrast reduction depends on many factors (haze optical thickness, vertical distribution, single scattering albedo, scattering geometry, spatial scale). Titan's haze is strongly forward scattering even near 1-µm wavelength and many RT codes do a poor job. Fortunately the problem is more tractable at longer wavelengths. We show how data from the Cassini VIMS and ISS instruments can be used to understand surface contrast and atmospheric haze properties.

  16. Dispersing powders in liquids

    CERN Document Server

    Nelson, RD

    1988-01-01

    This book provides powder technologists with laboratory procedures for selecting dispersing agents and preparing stable dispersions that can then be used in particle size characterization instruments. Its broader goal is to introduce industrial chemists and engineers to the phenomena, terminology, physical principles, and chemical considerations involved in preparing and handling dispersions on a commercial scale. The book introduces novices to: - industrial problems due to improper degree of dispersion; - the nomenclature used in describing particles; - the basic physica

  17. Angle Dependence of the Orbital Magnetoresistance in Bismuth

    Directory of Open Access Journals (Sweden)

    Aurélie Collaudin

    2015-06-01

    Full Text Available We present an extensive study of angle-dependent transverse magnetoresistance in bismuth, with a magnetic field perpendicular to the applied electric current and rotating in three distinct crystallographic planes. The observed angular oscillations are confronted with the expectations of semiclassic transport theory for a multivalley system with anisotropic mobility and the agreement allows us to quantify the components of the mobility tensor for both electrons and holes. A quadratic temperature dependence is resolved. As Hartman argued long ago, this indicates that inelastic resistivity in bismuth is dominated by carrier-carrier scattering. At low temperature and high magnetic field, the threefold symmetry of the lattice is suddenly lost. Specifically, a 2π/3 rotation of magnetic field around the trigonal axis modifies the amplitude of the magnetoresistance below a field-dependent temperature. By following the evolution of this anomaly as a function of temperature and magnetic field, we map the boundary in the (field, temperature plane separating two electronic states. In the less symmetric state, confined to low temperature and high magnetic field, the three Dirac valleys cease to be rotationally invariant. We discuss the possible origins of this spontaneous valley polarization, including a valley-nematic scenario.

  18. Magneto-photoconductivity of three dimensional topological insulator bismuth telluride

    Science.gov (United States)

    Cao, Bingchen; Eginligil, Mustafa; Yu, Ting

    2018-03-01

    Magnetic field dependence of the photocurrent in a 3D topological insulator is studied. Among the 3D topological insulators bismuth telluride has unique hexagonal warping and spin texture which has been studied by photoemission, scanning tunnelling microscopy and transport. Here, we report on low temperature magneto-photoconductivity, up to 7 T, of two metallic bismuth telluride topological insulator samples with 68 and 110 nm thicknesses excited by 2.33 eV photon energy along the magnetic field perpendicular to the sample plane. At 4 K, both samples exhibit negative magneto-photoconductance below 4 T, which is as a result of weak-antilocalization of Dirac fermions similar to the previous observations in electrical transport. However the thinner sample shows positive magneto-photoconductance above 4 T. This can be attributed to the coupling of surface states. On the other hand, the thicker sample shows no positive magneto-photoconductance up to 7 T since there is only one surface state at play. By fitting the magneto-photoconductivity data of the thicker sample to the localization formula, we obtain weak antilocalization behaviour at 4, 10, and 20 K, as expected; however, weak localization behaviour at 30 K, which is a sign of surface states masked by bulk states. Also, from the temperature dependence of phase coherence length bulk carrier-carrier interaction is identified separately from the surface states. Therefore, it is possible to distinguish surface states by magneto-photoconductivity at low temperature, even in metallic samples.

  19. Genotoxic effects of bismuth (III oxide nanoparticles by comet assay

    Directory of Open Access Journals (Sweden)

    Reecep Liman

    2015-06-01

    Full Text Available Bismuth oxide is one of the important transition metal oxides and it has been intensively studied due to their peculiar characteristics (semiconductor band gap, high refractive index, high dielectric permittivity, high oxygen conductivity, resistivity, photoconductivity and photoluminescence etc.. Therefore, it is used such as microelectronics, sensor technology, optical coatings, transparent ceramic glass manufacturing, nanoenergetic gas generator, biosensor for DNA hybridization, potential immobilizing platforms for glucose oxidase and polyphenol oxidase, fuel cells, a additive in paints, an astringent in a variety of medical creams and topical ointments, and for the determination of heavy metal ions in drinking water, mineral water and urine. In addition this, Bismuth (III oxide nanoparticles (BONPs are favorable for the biomolecules adsorption than regular sized particles because of their greater advantages and novel characteristics (much higher specific surface, greater surface free energy, and good electrochemical stability etc.. Genotoxic effects of BONPs were investigated on the root cells of Allium cepa by Comet assay. A. cepa roots were treated with the aqueous dispersions of BONPs at 5 different concentrations (12.5, 25, 50, 75, and 100 ppm for 4 h. A significant increase in DNA damage was also observed at all concentrations of BONPs except 12.5 ppm by Comet assay. The results were also analyzed statistically by using SPSS for Windows; Duncan’s multiple range test was performed. These result indicate that BONPs exhibit genotoxic activity in A. cepa root meristematic cells.

  20. Magnetic anisotropies in ultrathin bismuth iron garnet films

    International Nuclear Information System (INIS)

    Popova, Elena; Franco Galeano, Andres Felipe; Deb, Marwan; Warot-Fonrose, Bénédicte; Kachkachi, Hamid; Gendron, François; Ott, Frédéric

    2013-01-01

    Ultrathin bismuth iron garnet Bi 3 Fe 5 O 12 films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi 3 Fe 5 O 12 films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi 3 Fe 5 O 12 films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi 3 Fe 5 O 12 were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed

  1. Magnetic anisotropies in ultrathin bismuth iron garnet films

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Elena, E-mail: popova@physique.uvsq.fr [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Franco Galeano, Andres Felipe [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Deb, Marwan [Groupe d' Etude de la Matière Condensée (GEMaC), CNRS/Université de Versailles-Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles (France); Warot-Fonrose, Bénédicte [Centre d' Elaboration de Matériaux et d' Etudes Structurales (CEMES), CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS–Universidad de Zaragoza (Spain); Kachkachi, Hamid [Laboratoire PROcédés, Matériaux et Energie Solaire (PROMES), CNRS/Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, 66860 Perpignan (France); Gendron, François [Institut des NanoSciences de Paris (INSP), CNRS/Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, Boîte courrier 840, 75252 Paris Cedex 05 (France); Ott, Frédéric [Laboratoire Léon Brillouin (LLB), CNRS/CEA, Bâtiment 563, CEA Saclay, 91191 Gif sur Yvette Cedex (France); and others

    2013-06-15

    Ultrathin bismuth iron garnet Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on (001)-oriented gadolinium gallium garnet substrates. Film thickness varied from two to three dozens of unit cells. Bi{sub 3}Fe{sub 5}O{sub 12} films grow pseudomorphically on substrates up to a thickness of 20 nm, and then a lattice relaxation occurs. Magnetic properties of the films were studied as a function of bismuth iron garnet thickness. The magnetization and cubic anisotropy decrease with decreasing film thickness. The uniaxial magnetocrystalline anisotropy is constant for all film thicknesses. For two unit cell thick films, the easy magnetization axis changes from in-plane to perpendicular to the plane direction. Such a reorientation takes place as a result of the competition of constant uniaxial perpendicular anisotropy with weakening film magnetization. - Highlights: ► Ultrathin Bi{sub 3}Fe{sub 5}O{sub 12} films were grown epitaxially on structure-matching substrates. ► Magnetic properties of Bi{sub 3}Fe{sub 5}O{sub 12} were studied down to the thickness of 2.5 nm. ► Reorientation of easy magnetization axis as a function of film thickness was observed.

  2. Superconductivity in Bismuth. A New Look at an Old Problem.

    Science.gov (United States)

    Mata-Pinzón, Zaahel; Valladares, Ariel A; Valladares, Renela M; Valladares, Alexander

    2016-01-01

    To investigate the relationship between atomic topology, vibrational and electronic properties and superconductivity of bismuth, a 216-atom amorphous structure (a-Bi216) was computer-generated using our undermelt-quench approach. Its pair distribution function compares well with experiment. The calculated electronic and vibrational densities of states (eDOS and vDOS, respectively) show that the amorphous eDOS is about 4 times the crystalline at the Fermi energy, whereas for the vDOS the energy range of the amorphous is roughly the same as the crystalline but the shapes are quite different. A simple BCS estimate of the possible crystalline superconducting transition temperature gives an upper limit of 1.3 mK. The e-ph coupling is more preponderant in a-Bi than in crystalline bismuth (x-Bi) as indicated by the λ obtained via McMillan's formula, λc = 0.24 and experiment λa = 2.46. Therefore with respect to x-Bi, superconductivity in a-Bi is enhanced by the higher values of λ and of eDOS at the Fermi energy.

  3. System design study of small lead-bismuth cooled reactor

    International Nuclear Information System (INIS)

    Chikazawa, Yoshitaka; Hori, Toru; Konomura, Mamoru

    2003-07-01

    In phase II of the feasibility study of JNC, we will make a concept of a dispersion power source reactor with various requirements, such as economical competitiveness and safety. In the study of a small lead-bismuth cooled reactor, a concept whose features are long life core, inherent safety, natural convection of cooling system and steam generators in the reactor vessel has been designed since 2000. The investigations which have been done in 2002 are shown as follows; Safety analysis of UTOP considering uncertainty of reactivity. Possibility of reduction of number of control rods. Estimation of construction cost. Transient analyses of UTOP have been done in considering uncertainty of reactivity in order to show the inherent safety in the probabilistic method. And the inherent safety in UTOP is realized under the condition of considering uncertainty. Transient analyses of UTOP with various numbers of control rods have been done and it is suggested that there is possibility of reduction of the number of control rods considering accident managements. The method of cost estimation is a little modified. The cost of reactor vessel is estimated from that of medium sized lead-bismuth cooled reactor and the estimation of a purity control system is by coolant volume flow rate. The construction cost is estimated 850,000yen/kWe. (author)

  4. Electrodeposition of bismuth alloys by the controlled potential method

    International Nuclear Information System (INIS)

    Lopez Alvarez, F.A.

    1993-01-01

    We worked with the electrodeposition of three bismuth alloys, the composition of the first electrolyte was: 0.3 g/l. Bi; 20 g/l. Ni; and the conditions were pH = 5.2 - 5.6; T = 25 Centigrade degrees; current density 0.3 A / dm 2 - 6.6 A / dm 2 . Following alloy was between Bi - Pb, composition of the electrolyte was 3.18 g/l. Bi (metallic); 31.81 g/l. Pb (Pb(NO 3 ) 2 ) pH : 1; T = 20 Centigrade degrees; current density 10.20 A/dm 2 . The third electrolyte was Bi-Cu, its composition was: 20.89 g/l. Bi; (metallic) 63.54 g/l Cu (Cu(NO 3 ) 2 ) pH : 1.5 - 1.8; T = 25-30 Centigrade degrees; current density 1-2 A/dm 2 . The best results were obtained with the third electrolyte. The purpose of this work was to experiment with different parameters like temperature, pH and the electrolyte concentration to obtain a bismuth alloy. (Author)

  5. Spark plasma sintered bismuth telluride-based thermoelectric materials incorporating dispersed boron carbide

    Energy Technology Data Exchange (ETDEWEB)

    Williams, H.R., E-mail: hugo.williams@leicester.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Ambrosi, R.M. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Chen, K. [School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Friedman, U. [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Ning, H.; Reece, M.J. [School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Robbins, M.C.; Simpson, K. [European Thermodynamics Ltd., 8 Priory Business Park, Wistow Road, Kibworth LE8 0R (United Kingdom); Stephenson, K. [European Space Agency, ESTEC TEC-EP, Keplerlaan 1, 2201AZ Noordwijk (Netherlands)

    2015-03-25

    Highlights: • Nano-B{sub 4}C reinforced Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} p-type thermoelectric produced by SPS. • Addition of B{sub 4}C up to 0.2 vol% to SPS’d material has little effect on zT. • Vickers hardness improved by 27% by adding 0.2 vol% B{sub 4}C. • Fracture toughness of SPS material: K{sub IC} = 0.80 MPa m{sup 1/2} by SEVNB. • Mechanical properties much better than commercial directionally solidified material. - Abstract: The mechanical properties of bismuth telluride based thermoelectric materials have received much less attention in the literature than their thermoelectric properties. Polycrystalline p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} materials were produced from powder using spark plasma sintering (SPS). The effects of nano-B{sub 4}C addition on the thermoelectric performance, Vickers hardness and fracture toughness were measured. Addition of 0.2 vol% B{sub 4}C was found to have little effect on zT but increased hardness by approximately 27% when compared to polycrystalline material without B{sub 4}C. The K{sub IC} fracture toughness of these compositions was measured as 0.80 MPa m{sup 1/2} by Single-Edge V-Notched Beam (SEVNB). The machinability of polycrystalline materials produced by SPS was significantly better than commercially available directionally solidified materials because the latter is limited by cleavage along the crystallographic plane parallel to the direction of solidification.

  6. Bismuth zinc vanadate, BiZn2VO6: New crystal structure type and electronic structure

    International Nuclear Information System (INIS)

    Eliziario Nunes, Sayonara; Wang, Chun-Hai; So, Karwei; Evans, John S.O.; Evans, Ivana Radosavljević

    2015-01-01

    We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn 2 VO 6 , known for its visible light photocatalytic activity. The crystal structure has been solved from laboratory powder X-ray diffraction data using the repeated minimisations from random starting values method. BiZn 2 VO 6 adopts a new structure type, based on the following building blocks: corner- and edge-sharing ZnO 4 tetrahedra, ZnO 6 octahedra and VO 4 tetrahedra, and Bi 2 O 12 dimers. It is the only known member of the BiM 2 AO 6 (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family which does not appear to be structurally closely related to others. The electronic structure of BiZn 2 VO 6 , calculated by DFT methods, shows that it is an indirect gap semiconductor with a calculated band gap of 1.6 eV, which compares favourably to the experimentally measured value of 2.4 eV. - Graphical abstract: The crystal structure of BiZn 2 VO 6 , a new structure type in the BiM 2 AO 6 (M=Mg, Ca, Cd, Cu, Pb, Mn, Zn; A=V, P, As) family. - Highlights: • Structure solution from PXRD data by repeated minimisations from random starting values. • New structure type in the BiM 2 AO 6 (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family. • Electronic structure calculation

  7. Container for nuclear fuel powders

    International Nuclear Information System (INIS)

    Etheredge, B.F.; Larson, R.I.

    1982-01-01

    A critically safe container is disclosed for the storage and rapid discharge of enriched nuclear fuel material in powder form is disclosed. The container has a hollow, slab-shaped container body that has one critically safe dimension. A powder inlet is provided on one side wall of the body adjacent to a corner thereof and a powder discharge port is provided at another corner of the body approximately diagonal the powder inlet. Gas plenum for moving the powder during discharge are located along the side walls of the container adjacent the discharge port

  8. Exfoliation and thermal transformations of Nb-substituted layered titanates

    DEFF Research Database (Denmark)

    Song, H.; Sjåstad, Anja O.; Fjellvåg, Helmer

    2011-01-01

    Single-layer Nb-substituted titanate nanosheets of ca. 1 nm thickness were obtained by exfoliating tetrabutylammonium (TBA)-intercalated Nb-substituted titanates in water. AFM images and turbidity measurements reveal that the exfoliated nanosheets crack and corrugate when sonicated. Upon heating...... factors for increasing the transformation temperatures for conversion of the nanosheets to anatase and finally into rutile. It is further tempting to link the delay in crystallization to morphology limitations originating from the nanosheets. The present work shows that layered Nb-titanates...

  9. Progressive Climate Change on Titan: Implications for Habitability

    Science.gov (United States)

    Moore, J. M.; A. D. Howard

    2014-01-01

    Titan's landscape is profoundly shaped by its atmosphere and comparable in magnitude perhaps with only the Earth and Mars amongst the worlds of the Solar System. Like the Earth, climate dictates the intensity and relative roles of fluvial and aeolian activity from place to place and over geologic time. Thus Titan's landscape is the record of climate change. We have investigated three broad classes of Titan climate evolution hypotheses (Steady State, Progressive, and Cyclic), regulated by the role, sources, and availability of methane. We favor the Progressive hypotheses, which we will outline here, then discuss their implication for habitability.

  10. Cosmic-rays induced Titan tholins and their astrobiological significances

    Science.gov (United States)

    Kobayashi, Kensei; Taniuchi, Toshinori; Hosogai, Tomohiro; Kaneko, Takeo; Takano, Yoshinori; Khare, Bishun; McKay, Chris

    Titan is the largest satellite of Saturn. It is quite unique satellite since it has a dense atmosphere composed of nitrogen and methane, and has been sometimes considered as a model of primitive Earth. In Titan atmosphere, a wide variety of organic compounds and mists made of complex organics. Such solid complex organics are often referred to as tholins. A number of laboratory experiments simulating reactions in Titan atmosphere have been conducted. In most of them, ultraviolet light and discharges (simulating actions of electrons in Saturn magnetosphere) were used, which were simulation of the reactions in upper dilute atmosphere of Titan. We examined possible formation of organic compounds in the lower dense atmosphere of Titan, where cosmic rays are major energies. A Mixture of 35 Torr of methane and 665 Torr of nitrogen was irradiated with high-energy protons (3 MeV) from a van de Graaff accelerator (TIT, Japan) or from a Tandem accelerator (TIARA, QUBS, JAEA, Japan). In some experiments, 13 C-labelled methane was used. We also performed plasma discharges in a mixture of methane (10 %) and nitrogen (90 %) to simulate the reactions in the upper atmosphere of Titan. Solid products by proton irradiation and those by plasma discharges are hereafter referred to as PI-tholins and PD-tholins, respectively. The resulting PI-tholins were observed with SEM and AFM. They were characterized by pyrolysis-GC/MS, gel permeation chromatography, FT-IR, etc. Amino acids in PI-and PD-tholins were analyzed by HPLC, GC/MS and MALDI-TOF-MS after acid hydrolysis. 18 O-Labelled water was used in some cases during hydrolysis. Filamentary and/or globular-like structures were observed by SEM and AFM. By pyrolysis-GC/MS of PI-tholins, ammonia and hydrogen cyanide were detected, which was the same as the results obtained in Titan atmosphere during the Huygens mission. A wide variety of amino acids were detected after hydrolysis of both tholins. It was proved that oxygen atoms in the amino

  11. Decontamination of 2-chloroethyl ethylsulfide using titanate nanoscrolls

    Science.gov (United States)

    Kleinhammes, Alfred; Wagner, George W.; Kulkarni, Harsha; Jia, Yuanyuan; Zhang, Qi; Qin, Lu-Chang; Wu, Yue

    2005-08-01

    Titanate nanoscrolls, a recently discovered variant of TiO 2 nanocrystals, are tested as reactive sorbent for chemical warfare agent (CWA) decontamination. The large surface area of the uncapped tubules provides the desired rapid absorption of the contaminant while water molecules, intrinsic constituents of titanate nanoscrolls, provide the necessary chemistry for hydrolytic reaction. In this study the decomposition of 2-chloroethyl ethylsulfide (CEES), a simulant for the CWA mustard, was monitored using 13C NMR. The NMR spectra reveal reaction products as expected from the hydrolysis of CEES. This demonstrates that titanate nanoscrolls could potentially be employed as a decontaminant for CWAs.

  12. Mission Techniques for Exploring Saturn's icy moons Titan and Enceladus

    Science.gov (United States)

    Reh, Kim; Coustenis, Athena; Lunine, Jonathan; Matson, Dennis; Lebreton, Jean-Pierre; Vargas, Andre; Beauchamp, Pat; Spilker, Tom; Strange, Nathan; Elliott, John

    2010-05-01

    The future exploration of Titan is of high priority for the solar system exploration community as recommended by the 2003 National Research Council (NRC) Decadal Survey [1] and ESA's Cosmic Vision Program themes. Cassini-Huygens discoveries continue to emphasize that Titan is a complex world with very many Earth-like features. Titan has a dense, nitrogen atmosphere, an active climate and meteorological cycles where conditions are such that the working fluid, methane, plays the role that water does on Earth. Titan's surface, with lakes and seas, broad river valleys, sand dunes and mountains was formed by processes like those that have shaped the Earth. Supporting this panoply of Earth-like processes is an ice crust that floats atop what might be a liquid water ocean. Furthermore, Titan is rich in very many different organic compounds—more so than any place in the solar system, except Earth. The Titan Saturn System Mission (TSSM) concept that followed the 2007 TandEM ESA CV proposal [2] and the 2007 Titan Explorer NASA Flagship study [3], was examined [4,5] and prioritized by NASA and ESA in February 2009 as a mission to follow the Europa Jupiter System Mission. The TSSM study, like others before it, again concluded that an orbiter, a montgolfiѐre hot-air balloon and a surface package (e.g. lake lander, Geosaucer (instrumented heat shield), …) are very high priority elements for any future mission to Titan. Such missions could be conceived as Flagship/Cosmic Vision L-Class or as individual smaller missions that could possibly fit within NASA's New Frontiers or ESA's Cosmic Vision M-Class budgets. As a result of a multitude of Titan mission studies, several mission concepts have been developed that potentially fit within various cost classes. Also, a clear blueprint has been laid out for early efforts critical toward reducing the risks inherent in such missions. The purpose of this paper is to provide a brief overview of potential Titan (and Enceladus) mission

  13. The Exploration of Titan and the Saturnian System

    Science.gov (United States)

    Coustenis, Athena

    The exploration of the outer solar system and in particular of the giant planets and their environments is an on-going process with the Cassini spacecraft currently around Saturn, the Juno mission to Jupiter preparing to depart and two large future space missions planned to launch in the 2020-2025 time frame for the Jupiter system and its satellites (Europa and Ganymede) on the one hand, and the Saturnian system and Titan on the other hand [1,2]. Titan, Saturn's largest satellite, is the only other object in our Solar system to possess an extensive nitrogen atmosphere, host to an active organic chemistry, based on the interaction of N2 with methane (CH4). Following the Voyager flyby in 1980, Titan has been intensely studied from the ground-based large telescopes (such as the Keck or the VLT) and by artificial satellites (such as the Infrared Space Observatory and the Hubble Space Telescope) for the past three decades. Prior to Cassini-Huygens, Titan's atmospheric composition was thus known to us from the Voyager missions and also through the explorations by the ISO. Our perception of Titan had thus greatly been enhanced accordingly, but many questions remained as to the nature of the haze surrounding the satellite and the composition of the surface. The recent revelations by the Cassini-Huygens mission have managed to surprise us with many discoveries [3-8] and have yet to reveal more of the interesting aspects of the satellite. The Cassini-Huygens mission to the Saturnian system has been an extraordinary success for the planetary community since the Saturn-Orbit-Insertion (SOI) in July 2004 and again the very successful probe descent and landing of Huygens on January 14, 2005. One of its main targets was Titan. Titan was revealed to be a complex world more like the Earth than any other: it has a dense mostly nitrogen atmosphere and active climate and meteorological cycles where the working fluid, methane, behaves under Titan conditions the way that water does on

  14. Synthesis, by alkaline fusion of zirconia from zirconite: characterization and preparation of lead zirconate-titanate

    International Nuclear Information System (INIS)

    Zaghete, M.A.

    1985-01-01

    Zirconium oxide was prepared from zirconite by alkaline fusion. The purity of zirconia was determined by atomic absorption spectroscopy and was found to be 99,94 wt%. In order to prepare en unglomerated and dry hidrous zirconia powder it was used alcohol and acetone for washing and gel suspension; control of the drying rate; and control of the atmosphere and temperature of the oven. The physical characteristics of the hidrous zirconia powder were determined after calcining in several conditions. The zirconia obtained by calcining at 800 0 C during 5 hours (13,9m 2 /g) was used with titanium oxide (7,6m 2 /g and lead oxide (0,6m 2 /g) to prepare a lead zirconate-titanate (PZT) with composition Pb(Zr 0,5 Ti 0,5 O 3 . Two different procedures were used to obtain high densits PZT pellets: in the first procedure the misture of the oxide powder with above composition were reacted at 850 0 C for 4 hours. Then the powder was pressed and sintered at 1200 0 C during 4 and 6 hours; in the second procedure the mixture of unreacted oxide were pressed in pellets and then reacted at 850 0 C during 4 hours and sintered at 1200 0 C during 4 and 6 hours. The apparent density of the sintered pellets were determined By mercury displacement and ranged from 7,25 to 7,39 g/cm 3 for the compacts obtained by the second procedure and from 8,08 to 8,10g/cm 3 for the compacts obtained by the first procedure. The microstructure observed by scanning electron microscopy showed that sintered compact obtained by the first procedure has a more homogeneous size distribution when compared with samples obtained be the second procedure. (author) [pt

  15. Helicobacter pylori second-line rescue therapy with levofloxacin- and bismuth-containing quadruple therapy, after failure of standard triple or non-bismuth quadruple treatments.

    Science.gov (United States)

    Gisbert, J P; Romano, M; Gravina, A G; Solís-Muñoz, P; Bermejo, F; Molina-Infante, J; Castro-Fernández, M; Ortuño, J; Lucendo, A J; Herranz, M; Modolell, I; Del Castillo, F; Gómez, J; Barrio, J; Velayos, B; Gómez, B; Domínguez, J L; Miranda, A; Martorano, M; Algaba, A; Pabón, M; Angueira, T; Fernández-Salazar, L; Federico, A; Marín, A C; McNicholl, A G

    2015-04-01

    The most commonly used second-line Helicobacter pylori eradication regimens are bismuth-containing quadruple therapy and levofloxacin-containing triple therapy, both offering suboptimal results. Combining bismuth and levofloxacin may enhance the efficacy of rescue eradication regimens. To evaluate the efficacy and tolerability of a second-line quadruple regimen containing levofloxacin and bismuth in patients whose previous H. pylori eradication treatment failed. This was a prospective multicenter study including patients in whom a standard triple therapy (PPI-clarithromycin-amoxicillin) or a non-bismuth quadruple therapy (PPI-clarithromycin-amoxicillin-metronidazole, either sequential or concomitant) had failed. Esomeprazole (40 mg b.d.), amoxicillin (1 g b.d.), levofloxacin (500 mg o.d.) and bismuth (240 mg b.d.) was prescribed for 14 days. Eradication was confirmed by (13) C-urea breath test. Compliance was determined through questioning and recovery of empty medication envelopes. Incidence of adverse effects was evaluated by questionnaires. 200 patients were included consecutively (mean age 47 years, 67% women, 13% ulcer). Previous failed therapy included: standard clarithromycin triple therapy (131 patients), sequential (32) and concomitant (37). A total of 96% took all medications correctly. Per-protocol and intention-to-treat eradication rates were 91.1% (95%CI = 87-95%) and 90% (95%CI = 86-94%). Cure rates were similar regardless of previous (failed) treatment or country of origin. Adverse effects were reported in 46% of patients, most commonly nausea (17%) and diarrhoea (16%); 3% were intense but none was serious. Fourteen-day bismuth- and levofloxacin-containing quadruple therapy is an effective (≥90% cure rate), simple and safe second-line strategy in patients whose previous standard triple or non-bismuth quadruple (sequential or concomitant) therapies have failed. © 2015 John Wiley & Sons Ltd.

  16. Preparation of superconductor precursor powders

    Science.gov (United States)

    Bhattacharya, Raghunath

    1998-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic and/or reduced particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of all metals in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  17. Lead removal from aqueous solutions by potassium titanate doped with silica; Remocion de plomo de soluciones acuosas por titanato de potasio dopado con silice

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar G, M. A.; Aguilar E, A. [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes No. 120, 31109 Chihuahua (Mexico); Gorokhovsky, A. V.; Escalante G, J. I. [Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Carretera Saltillo-Mty Km. 13, Apdo. Postal 663, Saltillo 25000, Coahuila (Mexico)], e-mail: mgzlz@hotmail.com

    2009-07-01

    This paper is related to elimination of Pb{sup 2+} ions from aqueous solutions by adsorption in potassium tetra titanate doped with silica. The adsorbent was prepared in the form of granules with pastes of potassium poly titanate (45 %), powdered Pyrex glass (5 %) and potato starch (50 %), which were extruded and thermally treated at 1100 C. The structural characteristic of the granulated adsorbent allows reducing the Pb concentration, from the solutions eluted through an adsorption column, to levels below the requirement of national standards. The effects of the time of saturation of the adsorbent and the ph of the solution were also investigated on the effectiveness of the adsorption of Pb. The mechanism of lead adsorption, by the developed adsorbent, is considered as a combination of adsorption, ion-exchange and co-precipitation processes. It is also shown that the lead-saturated adsorbent could be utilized to produce high-strength non-dangerous ceramic materials. (Author)

  18. Complexometric consequent titration of bismuth-titanium mixtures in the μg-region

    International Nuclear Information System (INIS)

    Schaefer, H.

    1975-01-01

    A quantitative method is described for the determination of microquantities of bismuth and titanium. Both metals are determined complexometrically with EDTA and potentiometric equivalence point indication using a Cu-ion sensitive electrode in a consequent titration. The analysis is conducted as back-titration with standard Cu-solution. The relative error of the determination is 0.8% for bismuth (50-100 μg) and for titanium (10-30 μg) at 1.0%. Under the chosen conditions, it is possible to determine as little as 15 μg bismuth and 5 μg titanium by means of this procedure. (author)

  19. Specificities of reactor coolant pumps units with lead and lead-bismuth coolant

    International Nuclear Information System (INIS)

    Beznosov, A.V.; Anotonenkov, M.A.; Bokov, P.A.; Baranova, V.S.; Kustov, M.S.

    2009-01-01

    The analysis results of impact of lead and lead-bismuth coolants specific properties on the coolants flow features in flow channels of the main and auxiliary circulating pumps are presented. Impossibility of cavitation initiation in flow channels of vane pumps pumping lead and lead-bismuth coolants was demonstrated. The experimental research results of discontinuity of heavy liquid metal coolant column were presented and conditions of gas cavitation initiation in coolant flow were discussed. Invalidity of traditional calculation methods of water and sodium coolants circulation pumps calculations for lead and lead-bismuth coolants circulation pumps was substantiated [ru

  20. Topological Insulator State in Thin Bismuth Films Subjected to Plane Tensile Strain

    Science.gov (United States)

    Demidov, E. V.; Grabov, V. M.; Komarov, V. A.; Kablukova, N. S.; Krushel'nitskii, A. N.

    2018-03-01

    The results of experimental examination of galvanomagnetic properties of thin bismuth films subjected to plane tensile strain resulting from the difference in thermal expansion coefficients of the substrate material and bismuth are presented. The resistivity, the magnetoresistance, and the Hall coefficient were studied at temperatures ranging from 5 to 300 K in magnetic fields as strong as 0.65 T. Carrier densities were calculated. A considerable increase in carrier density in films thinner than 30 nm was observed. This suggests that surface states are more prominent in thin bismuth films on mica substrates, while the films themselves may exhibit the properties of a topological insulator.

  1. A Report of Clouds on Titan

    Science.gov (United States)

    Corlies, Paul; Hayes, Alexander; Adamkovics, Mate; Rodriguez, Sebastien; Kelland, John; Turtle, Elizabeth P.; Mitchell, Jonathan; Lora, Juan M.; Rojo, Patricio; Lunine, Jonathan I.

    2017-10-01

    We present in this work a detailed analysis of many of the clouds in the Cassini Visual and Infrared Mapping Spectrometer (VIMS) dataset in order to understand their global and seasonal properties. Clouds are one of the few direct observables in Titan’s atmosphere (Griffith et al 2009, Rodriguez et al 2009, Adamkovics et al 2010), and so determining their characteristics allows for a better understanding of surface atmosphere interactions, winds, transport of volatile material, and general circulation. We find the clouds on Titan generally reside in at 5-15km altitude, which agrees with previous modelling efforts (Rafkin et al. 2015), as well as a power law distribution for cloud optical depth. We assume an average cloud droplet size of 100um. No seasonal dependence is observed with either cloud altitude or optical depth, suggesting there is no preferred seasonal formation mechanisms. Combining these characteristics with cloud size (Kelland et al 2017) can trace the transport of volatiles in Titan’s atmosphere, which can be compared against general circulation models (GCMs) (Lora et al 2015). We also present some specific analysis of interesting cloud systems including hypothesized surface fogs (Brown et al 2009) and orographic cloud formation (Barth et al 2010, Corlies et al 2017). In this analysis we use a correlation between Cassini VIMS and RADAR observations as well as an updated topographic map of Titan’s southern hemisphere to better understand the role that topography plays in influencing and driving atmospheric phenomena.Finally, with the end of the Cassini mission, ground based observing now acts as the only means with which to observe clouds on Titan. We present an update of an ongoing cloud campaign to search for clouds on Titan and to understand their seasonal evolution.References:Adamkovics et al. 2010, Icarus 208:868Barth et al. 2010, Planet. Space Sci. 58:1740Corlies et al. 2017, 48th LPSC, 2870CGriffith et al. 2009, ApJ 702:L105Kelland et al

  2. Chemical structure of bismuth compounds determines their gastric ulcer healing efficacy and anti-Helicobacter pylori activity.

    Science.gov (United States)

    Sandha, G S; LeBlanc, R; Van Zanten, S J; Sitland, T D; Agocs, L; Burford, N; Best, L; Mahoney, D; Hoffman, P; Leddin, D J

    1998-12-01

    The recognition of the role of Helicobacter pylori in the pathogenesis of peptic ulcer disease has led to renewed interest in bismuth pharmacology since bismuth compounds have both anti-Helicobacter pylori and ulcer healing properties. The precise chemical structure of current bismuth compounds is not known. This has hindered the development of new and potentially more efficacious formulations. We have created two new compounds, 2-chloro-1,3-dithia-2-bismolane (CDTB) and 1,2-[bis(1,3-dithia-2-bismolane)thio]ethane (BTBT), with known structure. In a rat model of gastric ulceration, BTBT was comparable to, and CDTB was significantly less effective than colloidal bismuth subcitrate in healing cryoprobe-induced ulcers. However, both BTBT and CDTB inhibited H. pylori growth in vitro at concentrations <1/10 that of colloidal bismuth subcitrate. The effects on ulcer healing are not mediated by suppression of acid secretion, pepsin inhibition, or prostaglandin production. Since all treated animals received the same amount of elemental bismuth, it appears that the efficacy of bismuth compounds varies with compound structure and is not simply dependent on the delivery of bismuth ion. Because the structure of the novel compounds is known, our understanding of the relationship of bismuth compound structure and to biologic activity will increase. In the future it may be possible to design other novel bismuth compounds with more potent anti-H. pylori and ulcer healing effects.

  3. The TITAN reversed-field-pinch fusion reactor study

    International Nuclear Information System (INIS)

    1990-01-01

    This paper on titan plasma engineering contains papers on the following topics: reversed-field pinch as a fusion reactor; parametric systems studies; magnetics; burning-plasma simulations; plasma transient operations; current drive; and physics issues for compact RFP reactors

  4. Cation interdiffusion in polycrystalline calcium and strontium titanate

    International Nuclear Information System (INIS)

    Butler, E.P.; Jain, H.; Smyth, D.M.

    1991-01-01

    This paper discusses a method that has been developed to study bulk lattice interdiffusion between calcium and strontium titanate by fabrication of a diffusion couple using cosintering. The measured interdiffusion coefficients, D(C), indicate that strontium impurity diffusion in calcium titanate occurs at a faster rate than calcium impurity diffusion in strontium titanate. These interdiffusion coefficients are composition independent when the concentration of the calcium cation exceeds that of the strontium cation; otherwise D(C) is strongly composition dependent. Investigations into the effect of cation nonstoichiometry give results that are consistent with a defect incorporation reaction in which excess TiO 2 , within the solid solubility limit, produces A-site cation vacancies as compensating defects. The interdiffusion coefficients increase with increasing concentrations of TiO 2 , so it is concluded that interdiffusion of these alkaline-earth cations in their titanates occurs via a vacancy mechanism

  5. METHANE GAS STABILIZES SUPERCOOLED ETHANE DROPLETS IN TITAN'S CLOUDS

    International Nuclear Information System (INIS)

    Wang, Chia C.; Lang, E. Kathrin; Signorell, Ruth

    2010-01-01

    Strong evidence for ethane clouds in various regions of Titan's atmosphere has recently been found. Ethane is usually assumed to exist as ice particles in these clouds, although the possible role of liquid and supercooled liquid ethane droplets has been recognized. Here, we report on infrared spectroscopic measurements of ethane aerosols performed in the laboratory under conditions mimicking Titan's lower atmosphere. The results clearly show that liquid ethane droplets are significantly stabilized by methane gas which is ubiquitous in Titan's nitrogen atmosphere-a phenomenon that does not have a counterpart for water droplets in Earth's atmosphere. Our data imply that supercooled ethane droplets are much more abundant in Titan's clouds than previously anticipated. Possibly, these liquid droplets are even more important for cloud processes and the formation of lakes than ethane ice particles.

  6. The Titanic Origin of Humans: The Melian Nymphs and Zagreus

    Directory of Open Access Journals (Sweden)

    Velvet Yates

    2010-11-01

    Full Text Available Hesiod's creation myth implies that the human race derived from the "ash tree nymphs" (meliai; the Neoplatonists, with their etymological arguments, seem to have this in mind in tracing human origins to the Titans' "limbs" (melea.

  7. Tut and the Titanic and Finding History Beneath the Sea.

    Science.gov (United States)

    Hennessey, Gail Skroback; Ballard, Robert

    1988-01-01

    Two articles discuss the controversy about exploration of the shipwrecked Titanic. Suggested are questions for discussion and activities to stimulate student interest and to explore ethical issues involved in the treatment of historic artifacts. (CB)

  8. Amphibious Quadcopter Swarm for the Exploration of Titan

    Science.gov (United States)

    Rajguru, A.; Faler, A. C.; Franz, B.

    2014-06-01

    This is a proposal for a low mass and cost effective mission architecture consisting of an amphibious quadcopter swarm flight vehicle system for the exploration of Titan's liquid methane lake, Ligeia Mare. The paper focuses on the EDL and operations.

  9. Simulating the 3-D Structure of Titan's Upper Atmosphere

    Science.gov (United States)

    Bell, J. M.; Waite, H.; Westlake, J.; Magee, B.

    2009-05-01

    We present results from the 3-D Titan Global Ionosphere-Thermosphere Model (Bell et al [2009], PSS, in review). We show comparisons between simulated N2, CH4, and H2 density fields and the in-situ data from the Cassini Ion Neutral Mass Spectrometer (INMS). We describe the temperature and wind fields consistent with these density calculations. Variations with local time, longitude, and latitude will be addressed. Potential plasma heating sources can be estimated using the 1-D model of De La Haye et al [2007, 2008] and the impacts on the thermosphere of Titan can be assessed in a global sense in Titan-GITM. Lastly, we will place these findings within the context of recent work in modeling the 2-D structure of Titan's upper atmosphere (Mueller-Wodarg et al [2008]).

  10. Diffraction. Powder, amorphous, liquid

    International Nuclear Information System (INIS)

    Sosnowska, I.M.

    1999-01-01

    Neutron powder diffraction is a unique tool to observe all possible diffraction effects appearing in crystal. High-resolution neutron diffractometers have to be used in this study. Analysis of the magnetic structure of polycrystalline materials requires the use of high-resolution neutron diffraction in the range of large interplanar distances. As distinguished from the double axis diffractometers (DAS), which show high resolution only at small interplanar distances, TOF (time-of-flight) diffractometry offers the best resolution at large interplanar distances. (K.A.)

  11. LARC powder prepreg system

    Science.gov (United States)

    Baucom, Robert M.; Marchello, Joseph M.

    1990-01-01

    Thermoplastic prepregs of LARC-TPI have been produced in a fluidized bed unit on spread continuous fiber tows. The powders are melted on the fibers by radiant heating to adhere the polymer to the fiber. This process produces tow prepreg uniformly without imposing severe stress on the fibers or requiring long high temperature residence times for the polymer. Unit design theory and operating correlations have been developed to provide the basis for scale up to commercial operation. Special features of the operation are the pneumatic tow spreader, fluidized bed and resin feed systems.

  12. Plasma environment of Titan: a 3-D hybrid simulation study

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-05-01

    Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

  13. Extrusion and properties of lead zirconate titanate piezoelectric ceramics

    DEFF Research Database (Denmark)

    Cai, S.; Millar, C.E.; Pedersen, L.

    1997-01-01

    The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investi......The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates...

  14. Titan Lifting Entry & Atmospheric Flight (T-LEAF) Science Mission

    Science.gov (United States)

    Lee, G.; Sen, B.; Ross, F.; Sokol, D.

    2016-12-01

    Northrop Grumman has been developing the Titan Lifting Entry & Atmospheric Flight (T-LEAF) sky rover to roam the lower atmosphere and observe at close quarters the lakes and plains of Saturn's ocean moon, Titan. T-LEAF also supports surface exploration and science by providing precision delivery of in-situ instruments to the surface of Titan. T-LEAF is a highly maneuverable sky rover and its aerodynamic shape (i.e., a flying wing) does not restrict it to following prevailing wind patterns on Titan, but allows mission operators to chart its course. This freedom of mobility allows T-LEAF to follow the shorelines of Titan's methane lakes, for example, or to target very specific surface locations. We will present a straw man concept of T-LEAF, including size, mass, power, on-board science payloads and measurement, and surface science dropsonde deployment CONOPS. We will discuss the various science instruments and their vehicle level impacts, such as meteorological and electric field sensors, acoustic sensors for measuring shallow depths, multi-spectral imagers, high definition cameras and surface science dropsondes. The stability of T-LEAF and its long residence time on Titan will provide for time to perform a large aerial survey of select prime surface targets deployment of dropsondes at selected locations surface measurements that are coordinated with on-board remote measurements communication relay capabilities to orbiter (or Earth). In this context, we will specifically focus upon key factors impacting the design and performance of T-LEAF science: science payload accommodation, constraints and opportunities characteristics of flight, payload deployment and measurement CONOPS in the Titan atmosphere. This presentation will show how these factors provide constraints as well as enable opportunities for novel long duration scientific studies of Titan's surface.

  15. The TITAN Reversed-Field Pinch fusion reactor study

    International Nuclear Information System (INIS)

    1988-03-01

    The TITAN Reversed-Field Pinch (RFP) fusion reactor study is a multi-institutional research effort to determine the technical feasibility and key developmental issues of an RFP fusion reactor, especially at high power density, and to determine the potential economics, operations, safety, and environmental features of high-mass-power-density fusion systems. The TITAN conceptual designs are DT burning, 1000 MWe power reactors based on the RFP confinement concept. The designs are compact, have a high neutron wall loading of 18 MW/m 2 and a mass power density of 700 kWe/tonne. The inherent characteristics of the RFP confinement concept make fusion reactors with such a high mass power density possible. Two different detailed designs have emerged: the TITAN-I lithium-vanadium design, incorporating the integrated-blanket-coil concept; and the TITAN-II aqueous loop-in-pool design with ferritic steel structure. This report contains a collection of 16 papers on the results of the TITAN study which were presented at the International Symposium on Fusion Nuclear Technology. This collection describes the TITAN research effort, and specifically the TITAN-I and TITAN-II designs, summarizing the major results, the key technical issues, and the central conclusions and recommendations. Overall, the basic conclusions are that high-mass power-density fusion reactors appear to be technically feasible even with neutron wall loadings up to 20 MW/m 2 ; that single-piece maintenance of the FPC is possible and advantageous; that the economics of the reactor is enhanced by its compactness; and the safety and environmental features need not to be sacrificed in high-power-density designs. The fact that two design approaches have emerged, and others may also be possible, in some sense indicates the robustness of the general findings

  16. Aerosol chemistry in Titan's ionosphere: simultaneous growth and etching processes

    Science.gov (United States)

    Carrasco, Nathalie; Cernogora, Guy; Jomard, François; Etcheberry, Arnaud; Vigneron, Jackie

    2016-10-01

    Since the Cassini-CAPS measurements, organic aerosols are known to be present and formed at high altitudes in the diluted and partially ionized medium that is Titan's ionosphere [1]. This unexpected chemistry can be further investigated in the laboratory with plasma experiments simulating the complex ion-neutral chemistry starting from N2-CH4 [2]. Two sorts of solid organic samples can be produced in laboratory experiments simulating Titan's atmospheric reactivity: grains in the volume and thin films on the reactor walls. We expect that grains are more representative of Titan's atmospheric aerosols, but films are used to provide optical indices for radiative models of Titan's atmosphere.The aim of the present study is to address if these two sorts of analogues are chemically equivalent or not, when produced in the same N2-CH4 plasma discharge. The chemical compositions of both these materials are measured by using elemental analysis, XPS analysis and Secondary Ion Mass Spectrometry. We find that films are homogeneous but significantly less rich in nitrogen and hydrogen than grains produced in the same experimental conditions. This surprising difference in their chemical compositions is explained by the efficient etching occurring on the films, which stay in the discharge during the whole plasma duration, whereas the grains are ejected after a few minutes [3]. The impact for our understanding of Titan's aerosols chemical composition is important. Our study shows that chemical growth and etching process are simultaneously at stake in Titan's ionosphere. The more the aerosols stay in the ionosphere, the more graphitized they get through etching process. In order to infer Titan's aerosols composition, our work highlights a need for constraints on the residence time of aerosols in Titan's ionosphere. [1] Waite et al. (2009) Science , 316, p. 870[2] Szopa et al. (2006) PSS, 54, p. 394[3] Carrasco et al. (2016) PSS, 128, p. 52

  17. Crystal structure of red lead titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L.A.; Peng, J.L.; Jiang, B. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Li, X. [Jilin Univ., Changchun, JL (China). Dept of Chemistry

    1998-09-01

    Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate 7 refs., 1 tab., 4 figs.

  18. Crystal structure of red lead titanate thin films

    International Nuclear Information System (INIS)

    Bursill, L.A.; Peng, J.L.; Jiang, B.; Li, X.

    1998-01-01

    Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate

  19. Plasma environment of Titan: a 3-D hybrid simulation study

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-05-01

    Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

  20. Does Titan have an Active Surface?

    Science.gov (United States)

    Nelson, R.

    2009-12-01

    Robert M. Nelson-1, L. W. Kamp-1, R. M. C. Lopes-1, D. L. Matson-1, R. L. Kirk-2, B. W. Hapke-3, M. D. Boryta-4, F. E. Leader-1, W. D. Smythe-1, K. L. Mitchell-1, K. H. Baines-1, R. Jaumann-5, C. Sotin-1, R. N. Clark-6, D. P. Cruikshank-7 , P. Drossart-8, J. I. Lunine-9, M. Combes-10, G. Bellucci-11, J.-P. Bibring-12, F. Capaccioni-11, P. Cerroni-11, A. Coradini-11, V. Formisano-11, G. Filacchione-11, Y. Langevin-12, T. B. McCord-13, V. Mennella-14, B. Sicardy-8, P. G. J. Irwin-15 ,J.C. Pearl-16 1-JPL, 4800 Oak Grove Drive, Pasadena CA 91109;2-USGS, Flagstaff; 3-U Pittsburgh; 4-Mt. San Antonio College; 5-DLR, Berlin;6-USGS Denver; 7-NASA AMES; 8-U Paris-Meudon; 9-U Arizona; 10- Obs de Paris; 11-INAF-ISAF Rome; 12-U Paris -Sud. Orsay; 13-Bear Flt Cntr. Winthrop WA;14-Obs Capodimonte Naples; 15-Clarendon Laboratory, Oxford, UK, 16-Goddard Space Flight Center, Greenbelt MD Surface changes on Saturn’s moon Titan have been reported during the Cassini spacecraft’s four-year orbital tour of the Saturnian system based on Cassini Visual and Infrared Mapping Spectrometer (VIMS) data [1]. Titan’s surface is hard to observe because it’s atmosphere is opaque at visual wavelengths due to absorption by methane in Titan’s atmosphere. VIMS is able to image the surface through “windows” at infrared wavelengths where the methane is relatively transparent [1,2]. VIMS infrared images find surface reflectance variability at Hotei Reggio (26S,78W) and suggest that the variability might be due to deposition, followed by coverage or dissipation, of ammonia frost. Subsequently, Cassini RADAR images found that Hotei Reggio, has lobate “flow” forms, consistent with the morphology of volcanic terrain [3]. Here we report the discovery of lobate “flow” patterns at Hotei Reggio based on VIMS infrared images taken during Cassini close flybys during 2008-2009. This new evidence is consistent with the suggestion that the brightness variability at Hotei Reggio is associated with

  1. What makes the difference in perovskite titanates?

    Science.gov (United States)

    Bussmann-Holder, Annette; Roleder, Krystian; Ko, Jae-Hyeon

    2018-06-01

    We have investigated in detail the lattice dynamics of five different perovskite titanates ATiO3 (A = Ca, Sr, Ba, Pb, Eu) where the A sites are occupied by +2 ions. In spite of the largely ionic character of these ions, the properties of these compounds differ substantially. They range from order/disorder like, to displacive ferroelectric, quantum paraelectric, and antiferromagnetic. All compounds crystallize in the cubic structure at high temperature and undergo structural phase transitions to tetragonal symmetry, partly followed by further transitions to lower symmetries. Since the TiO6 moiety is the essential electronic and structural unit, the question arises, what makes the significant difference between them. It is shown that the lattice dynamics of these compounds are very different, and that mode-mode coupling effects give rise to many distinct properties. In addition, the oxygen ion nonlinear polarizability plays a key role since it dominates the anharmonicity of these perovskites and determines the structural instability.

  2. Status and future application of pilot lead-bismuth target circuit TC-1 for ADS

    Energy Technology Data Exchange (ETDEWEB)

    Ignatiev, S.; Leonchuk, M.; Orlov, Y.; Pankratov, D.; Reshetnikova, O.; Suvorov, G.; Zabudko, A. [Institute for Physics and Power Engineering, Obninsk (Russian Federation); Stepanov, V.; Klimov, N. [Experimental and Design Organization, Gidropress, Podolsk (Russian Federation); Hechanova, A.; Ma, J. [Nevada Univ., Las Vegas, NV (United States); Li, N. [Los Alamos National Lab., NM (United States); Gudowski, W. [International Science and Technology Center, Moscow (Russian Federation)

    2007-07-01

    A complicated evolution, status and future application of the pilot molten lead-bismuth target circuit of 1 MW proton beam power (TC-1) as an important part of a target-blanket accelerator driven system (ADS), that has been developed, created and twice tested under the auspice of the International Science and Technology Center (ISTC), is analyzed. The target complex TC-1 is a circulation lead-bismuth loop whose beam window is made of ferritic steel EP-823 (this steel was used in the past as material of fuel rods cladding in reactors cooled with lead-bismuth). At present TC-1 is operating at coolant temperature up to 300 C degrees and will be used to study different issues linked to the use of lead-bismuth: -) interaction with air, water and hydrogen, -) different regimes of flow, -) corrosion, -) filtering, or -) slag formation.

  3. Shielding property of bismuth glass based on MCNP 5 and WINXCOM simulated calculation

    International Nuclear Information System (INIS)

    Zhang Zhicheng; Zhang Jinzhao; Liu Ze; Lu Chunhai; Chen Min

    2013-01-01

    Background: Currently, lead glass is widely used as observation window, while lead is toxic heavy metal. Purpose: Non-toxic materials and their shielding effects are researched in order to find a new material to replace lead containing material. Methods: The mass attenuation coefficients of bismuth silicate glass were investigated with gamma-ray's energy at 0.662 MeV, 1.17 MeV and 1.33 MeV, respectively, by MCNP 5 (Monte Carlo) and WINXCOM program, and compared with those of the lead glass. Results: With attenuation factor K, shielding and mechanical properties taken into consideration bismuth glass containing 50% bismuth oxide might be selected as the right material. Dose rate distributions of water phantom were calculated with 2-cm and 10-cm thick glass, respectively, irradiated by 137 Cs and 60 Co in turn. Conclusion: Results show that the bismuth glass may replace lead glass for radiation shielding with appropriate energy. (authors)

  4. Corrosion by liquid lead and lead-bismuth: experimental results review and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jinsuo [Los Alamos National Laboratory

    2008-01-01

    Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

  5. Titan atmospheric composition by hypervelocity shock layer analysis

    International Nuclear Information System (INIS)

    Nelson, H.F.; Park, C.; Whiting, E.E.

    1989-01-01

    The Cassini Mission, a NASA/ESA cooperative project which includes a deployment of probe into the atmosphere of Titan, is described, with particular attention given to the shock radiometer experiment planned for the Titan probe for the analysis of Titan's atmosphere. Results from a shock layer analysis are presented, demonstrating that the mole fractions of the major species (N2, CH4, and, possibly Ar) in the Titan atmosphere can be successfully determined by the Titan-probe radiometer, by measuring the intensity of the CN(violet) radiation emitted in the shock layer during the high velocity portion of the probe entry between 200 and 400 km altitude. It is shown that the sensitivity of the CN(violet) radiation makes it possible to determine the mole fractions of N2, CH4, and Ar to about 0.015, 0.003, and 0.01, respectively, i.e., much better than the present uncertainties in the composition of Titan atmosphere. 29 refs

  6. Experimental basis for a Titan probe organic analysis

    International Nuclear Information System (INIS)

    Mckay, C.P.; Scattergood, T.W.; Borucki, W.J.; Kasting, J.F.; Miller, S.L.; California Univ., San Diego, La Jolla)

    1986-01-01

    The recent Voyager flyby of Titan produced evidence for at least nine organic compounds in that atmosphere that are heavier than methane. Several models of Titan's atmosphere, as well as laboratory simulations, suggest the presence of organics considerably more complex that those observed. To ensure that the in situ measurements are definitive with respect to Titan's atmosphere, experiment concepts, and the related instrumentation, must be carefully developed specifically for such a mission. To this end, the possible composition of the environment to be analyzed must be bracketed and model samples must be provided for instrumentation development studies. Laboratory studies to define the optimum flight experiment and sampling strategy for a Titan entry probe are currently being conducted. Titan mixtures are being subjected to a variety of energy sources including high voltage electron from a DC discharge, high current electric shock, and laser detonation. Gaseous and solid products are produced which are then analyzed. Samples from these experiements are also provided to candidate flight experiments as models for instrument development studies. Preliminary results show that existing theoretical models for chemistry in Titan's atmosphere cannot adequetely explain the presence and abundance of all trace gases observed in these experiments

  7. Study of the dielectric properties of barium titanate-polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Pant, H.C. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Patra, M.K. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Verma, Aditya [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Vadera, S.R. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India); Kumar, N. [R and D Laboratory, Defence Laboratory, Camouflage Division, Defence Laboratory Ratanada Palace, Jodhpur 342011, Rajasthan (India)]. E-mail: nkjainjd@yahoo.com

    2006-07-15

    A comparative study of complex dielectric properties has been carried out at the X-band of microwave frequencies of composites of barium titanate (BaTiO{sub 3}) with two different polymer matrices: insulating polyaniline (PANI) powder (emeraldine base) and maleic resin. From these studies, it is observed that the composites of BaTiO{sub 3} with maleic resin show normal composite behavior and the dielectric constant follows the asymmetric Bruggeman model. In contrast, the composites of BaTiO{sub 3} with PANI show an unusual behavior wherein even at a low concentration of PANI (5 wt.%) there is a drastic reduction in the dielectric constant of BaTiO{sub 3}. This behavior of the dielectric constant is explained on the basis of coating of BaTiO{sub 3} particles by PANI which in turn is attributed to the highly surface adsorbing character. The materials have also been characterized using Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy and optical microscopy studies.

  8. Study of the dielectric properties of barium titanate-polymer composites

    International Nuclear Information System (INIS)

    Pant, H.C.; Patra, M.K.; Verma, Aditya; Vadera, S.R.; Kumar, N.

    2006-01-01

    A comparative study of complex dielectric properties has been carried out at the X-band of microwave frequencies of composites of barium titanate (BaTiO 3 ) with two different polymer matrices: insulating polyaniline (PANI) powder (emeraldine base) and maleic resin. From these studies, it is observed that the composites of BaTiO 3 with maleic resin show normal composite behavior and the dielectric constant follows the asymmetric Bruggeman model. In contrast, the composites of BaTiO 3 with PANI show an unusual behavior wherein even at a low concentration of PANI (5 wt.%) there is a drastic reduction in the dielectric constant of BaTiO 3 . This behavior of the dielectric constant is explained on the basis of coating of BaTiO 3 particles by PANI which in turn is attributed to the highly surface adsorbing character. The materials have also been characterized using Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy and optical microscopy studies

  9. On the origin of near-IR luminescence in SiO{sub 2} glass with bismuth as the single dopant. Formation of the photoluminescent univalent bismuth silanolate by SiO{sub 2} surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Romanov, A.N., E-mail: alexey.romanov@list.ru; Haula, E.V.; Shashkin, D.P.; Vtyurina, D.N.; Korchak, V.N.

    2017-03-15

    Near infrared photoluminescent bismuth(I) silanolate centers ((≡Si-O){sub 3}Si–O-Bi) were prepared on the surface of SiO{sub 2} xerogel, by the treatment in the vapors of bismuth(I) chloride. The optical properties of these groups are almost identical to that of photoluminescent centers in the bulk SiO{sub 2} glasses with bismuth as the single dopant. - Highlights: • univalent bismuth silanolate can be prepared on SiO{sub 2} surface by treatment in BiCl vapors. • univalent bismuth silanolate is responsible for NIR photoluminescence in Bi-doped SiO{sub 2} glass. • univalent bismuth silanolate is the active center in laser, operating on Bi-doped SiO{sub 2} fiber.

  10. Study of irradiation defects in bismuth by electric transport measurements

    International Nuclear Information System (INIS)

    Le Goff, M.

    1984-01-01

    Pure monocrystalline bismuth is irradiated near 4K by electrons of different energies. Irradiation effects are measured by galvanomagnetic properties at low temperature. Frenkel pairs created during irradiation have a strong effect on carrier mobilities. The data are quantitatively analyzed assuming a rigid band model. After irradiation with 1 MeV electrons, each Frankel pair created corresponds to a total charge of 0.14 electrons. This result obtained by magnetoresistance and Hall effect is confirmed by Shubnikov-de Haas experiments. There is a linear variation between the excess carrier density (p-n) and the Frenkel pair concentration. The more important step of annealing is observed around 40-50 K. This step is attributed to interstitial migration. Resistivity presents a minimum at low temperature after irradiation with electrons of energy over 1.3 MeV. This is explained by virtual bound levels near the Fermi level. The Kondo effect bound to magnetic defects is discussed [fr

  11. Ni-rich precipitates in a lead bismuth eutectic loop

    International Nuclear Information System (INIS)

    Kikuchi, K.; Saito, S.; Hamaguchi, D.; Tezuka, M.

    2010-01-01

    Solidified LBE was sampled from the specimens, electro-magnetic pump, filter, drain valve and oxygen sensor at the JAEA Lead Bismuth Loop-1 (JLBL-1) where the structural material was made of SS316. The concentration of Ni, Fe and Cr in LBE were analyzed by the Inductive Coupled Plasma atomic emission spectrometer. It was concluded that the solution of Ni into LBE was not saturated although the concentration of Fe and Cr almost achieved to the values in the literature. A needle-type structure appeared on the surface of solidified LBE inside the tube specimens. It was found to be Ni-rich precipitates by X-ray analyses (Field Emission Scanning Electron Microscope, FE-SEM). LBE samples collected from a circulating loop after discharging did not show the amount of impurities equivalent to the LBE bulk property.

  12. Ni-rich precipitates in a lead bismuth eutectic loop

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, K., E-mail: kikuchik@mx.ibaraki.ac.j [Ibaraki University, IQBRC, Tokai, Ibaraki 319-1106 (Japan); Saito, S.; Hamaguchi, D.; Tezuka, M. [J-PARC Center, JAEA, Tokai, Ibaraki 319-1195 (Japan)

    2010-03-15

    Solidified LBE was sampled from the specimens, electro-magnetic pump, filter, drain valve and oxygen sensor at the JAEA Lead Bismuth Loop-1 (JLBL-1) where the structural material was made of SS316. The concentration of Ni, Fe and Cr in LBE were analyzed by the Inductive Coupled Plasma atomic emission spectrometer. It was concluded that the solution of Ni into LBE was not saturated although the concentration of Fe and Cr almost achieved to the values in the literature. A needle-type structure appeared on the surface of solidified LBE inside the tube specimens. It was found to be Ni-rich precipitates by X-ray analyses (Field Emission Scanning Electron Microscope, FE-SEM). LBE samples collected from a circulating loop after discharging did not show the amount of impurities equivalent to the LBE bulk property.

  13. Ni-rich precipitates in a lead bismuth eutectic loop

    Science.gov (United States)

    Kikuchi, K.; Saito, S.; Hamaguchi, D.; Tezuka, M.

    2010-03-01

    Solidified LBE was sampled from the specimens, electro-magnetic pump, filter, drain valve and oxygen sensor at the JAEA Lead Bismuth Loop-1 (JLBL-1) where the structural material was made of SS316. The concentration of Ni, Fe and Cr in LBE were analyzed by the Inductive Coupled Plasma atomic emission spectrometer. It was concluded that the solution of Ni into LBE was not saturated although the concentration of Fe and Cr almost achieved to the values in the literature. A needle-type structure appeared on the surface of solidified LBE inside the tube specimens. It was found to be Ni-rich precipitates by X-ray analyses (Field Emission Scanning Electron Microscope, FE-SEM). LBE samples collected from a circulating loop after discharging did not show the amount of impurities equivalent to the LBE bulk property.

  14. Coolant Chemistry Control: Oxygen Mass Transport in Lead Bismuth Eutectic

    International Nuclear Information System (INIS)

    Weisenburger, A.; Mueller, G.; Bruzzese, C.; Glass, A.

    2015-01-01

    In lead-bismuth cooled transmutation systems, oxygen, dissolved in the coolant at defined quantities, is required for stable long-term operation by assuring the formation of protective oxide scales on structural steel surfaces. Extracted oxygen must be permanently delivered to the system and distributed in the entire core. Therefore, coolant chemistry control involves detailed knowledge on oxygen mass transport. Beside the different flow regimes a core might have stagnant areas at which oxygen delivery can only be realised by diffusion. The difference between oxygen transport in flow paths and in stagnant zones is one of the targets of such experiments. To investigate oxygen mass transport in flowing and stagnant conditions, a dedicated facility was designed based on computational fluid dynamics (CFD). CFD also was applied to define the position of oxygen sensors and ultrasonic Doppler velocimetry transducers for flow measurements. This contribution will present the test facility, design relevant CFD calculations and results of first tests performed. (authors)

  15. Lead-Bismuth technology ; corrosion resistance of structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ji Young; Park, Won Seok [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-02-01

    Lead-Bismuth (Pb-Bi) eutectic alloy was determined as a coolant material for the HYPER system being studied by KAERI. The Pb-Bi alloy as a coolant, has a number of the favorable thermo-physical and technological properties, while it is comparatively corrosive to the structural materials. It is necessary to solve this problem for providing a long failure-proof operation of the facilities with Pb-Bi coolant. It seems to be possible to maintain corrosion resistance on structural material up to 600 deg C by using of various technologies, but it needs more studies for application to large-scale NPPs. 22 refs., 11 figs., 7 tabs. (Author)

  16. Stimulated Raman scattering of sub-millimeter waves in bismuth

    Science.gov (United States)

    Kumar, Pawan; Tripathi, V. K.

    2007-12-01

    A high-power sub-millimeter wave propagating through bismuth, a semimetal with non-spherical energy surfaces, parametrically excites a space-charge mode and a back-scattered electromagnetic wave. The free carrier density perturbation associated with the space-charge wave couples with the oscillatory velocity due to the pump to derive the scattered wave. The scattered and pump waves exert a pondermotive force on electrons and holes, driving the space-charge wave. The collisional damping of the decay waves determines the threshold for the parametric instability. The threshold intensity for 20 μm wavelength pump turns out to be ˜2×1012 W/cm2. Above the threshold, the growth rate scales increase with ωo, attain a maximum around ωo=6.5ωp, and, after this, falls off.

  17. Radiopacity and histological assessment of Portland cement plus bismuth oxide.

    Science.gov (United States)

    Coutinho-Filho, Tauby; De-Deus, Gustavo; Klein, Leila; Manera, Gisele; Peixoto, Carla; Gurgel-Filho, Eduardo Diogo

    2008-12-01

    The present study evaluated the subcutaneous connective tissue reactions and the radiopacity of MTA, Portland cement (PC), and Portland cement plus bismuth oxide (BO). Forty rats were divided into 5 groups (n = 8 per group): A1: Control (empty capsule); A2: Pro-Root MTA; A3: PC; A4: PC + BO 1:1; and A5: PC + BO 2:1. Polyethylene tubes were filled with the test materials and standardized radiographic images were taken. Histological evaluation was done after 7 and 60 days. Student t test and Fisher's test were used in the statistical analysis (P A4 > A5 > A3. No differences were found for the tissue response in the 2 experimental periods. A positive correlation between BO concentration and radiopacity of PC was determined. The histological evaluation suggests that all studied materials were biocompatible at 7 and 60 days.

  18. High ionic conductivity in confined bismuth oxide-based heterostructures

    Directory of Open Access Journals (Sweden)

    Simone Sanna

    2016-12-01

    Full Text Available Bismuth trioxide in the cubic fluorite phase (δ-Bi2O3 exhibits the highest oxygen ionic conductivity. In this study, we were able to stabilize the pure δ-Bi2O3 at low temperature with no addition of stabilizer but only by engineering the interface, using highly coherent heterostructures made of alternative layers of δ-Bi2O3 and Yttria Stabilized Zirconia (YSZ, deposited by pulsed laser deposition. The resulting [δ-Bi2O3/YSZ] heterostructures are found to be stable over a wide temperature range (500-750 °C and exhibits stable high ionic conductivity over a long time comparable to the value of the pure δ-Bi2O3, which is approximately two orders of magnitude higher than the conductivity of YSZ bulk.

  19. High ionic conductivity in confined bismuth oxide-based heterostructures

    DEFF Research Database (Denmark)

    Sanna, Simone; Esposito, Vincenzo; Christensen, Mogens

    2016-01-01

    Bismuth trioxide in the cubic fluorite phase (δ-Bi2O3) exhibits the highest oxygen ionic conductivity. In this study, we were able to stabilize the pure -Bi2O3 at low temperature with no addition of stabilizer but only by engineering the interface, using highly coherent heterostructures made...... of alternative layers of δ-Bi2O3 and Yttria Stabilized Zirconia (YSZ), deposited by pulsed laser deposition. The resulting [δ-Bi2O3=YSZ] heterostructures are found to be stable over a wide temperature range (500-750 °C) and exhibits stable high ionic conductivity over a long time comparable to the value...... of the pure δ-Bi2O3, which is approximately two orders of magnitude higher than the conductivity of YSZ bulk....

  20. Study of bismuth minerals belonging to the mineralogical collection from the National Museum

    International Nuclear Information System (INIS)

    Baptista, A.; Baptista, N.R.

    1991-09-01

    With the purpose of searching the presence of Tellurium minerals in the Ouro Preto-Mariana country, Minas Gerais State, and considering the existence of a great number of minerals in which this element come across allied with Bismuth, samples of the mineralogical collection of the Museu Nacional, proceeding that region and classified as Bismuth minerals were studied by X-ray fluorescence analysis and diffractometric analysis. In this report the results of this research are presented. (Author)

  1. About thermo-electric properties of bismuth telluride doped by gadolinium

    International Nuclear Information System (INIS)

    Akperov, M.M.; Ismailov, Sh.S.; Shukyurova, A.A.

    2004-01-01

    Results of study of the Gd impurities effect on the bismuth telluride thermo-electric properties are presented. The experiment was carried out within the temperature range T=300-700 K. It is determined, that at temperature increase the energy level is appreciably closing up to bismuth telluride forbidden zone which makes up 0.16-0.24 eV. Such anomalous energy properties of gadolinium in telluride affect on material thermoelectric properties

  2. An acclerator-based installation of small power with the lead-bismuth coolant

    Energy Technology Data Exchange (ETDEWEB)

    Gorshkov, V.T.; Yefimov, E.I.; Novikova, N.N. [Research and Development Bereau, Podolsk (Russian Federation)] [and others

    1995-10-01

    The structure of the accelerator-based installation is described that includes the subcritical reactor-blanket with power 15 MW(h) cooled with lead-bismuth, the lead-bismuth flow target where a beam of {alpha}-particle is injected, the equipment of a primary and secondary curcuits. Some results of calculations and estimations are discussed that have been carried out to justify the target and blanket constructions. Some main characteristics of the installation are presented.

  3. Bismuth oxide nanorods based immunosensor for mycotoxin detection

    Energy Technology Data Exchange (ETDEWEB)

    Solanki, Pratima R., E-mail: pratimarsolanki@gmail.com [DST Centre for Biomolecular Electronics, CSIR-National Physical Laboratory, K.S. Krishnan Marg, New Delhi (India); Special Centre for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Singh, Jay [DST Centre for Biomolecular Electronics, CSIR-National Physical Laboratory, K.S. Krishnan Marg, New Delhi (India); Department of Applied Chemistry and Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Rupavali, Bharti [DST Centre for Biomolecular Electronics, CSIR-National Physical Laboratory, K.S. Krishnan Marg, New Delhi (India); Tiwari, Sachchidanand [Special Centre for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Malhotra, Bansi D., E-mail: bansi.malhotra@gmail.com [DST Centre for Biomolecular Electronics, CSIR-National Physical Laboratory, K.S. Krishnan Marg, New Delhi (India); Department of Biotechnology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India)

    2017-01-01

    We report results of the studies relating to fabrication of an efficient immunosensor based on bismuth oxide nanorods (nBi{sub 2}O{sub 3}), electrophoretically deposited onto indium-tin-oxide (ITO) coated glass substrate. This immunosensor was fabricated by immobilization of anti-aflatoxin monoclonal antibodies (Ab-AFB1) and bovine serum albumin (BSA) for aflatoxin B1 detection. The structural and morphological studies of n-Bi{sub 2}O{sub 3} have been carried out by XRD, UV–vis spectrophotometer; SEM, AFM and FTIR. It was found that the nBi{sub 2}O{sub 3} provided improved sensing characteristics to the electrode interface in terms of electroactive surface area, diffusion coefficient, charge transfer rate constant and electron transfer kinetics. The results of electrochemical response studies of this BSA/Ab-AFB1/nBi{sub 2}O{sub 3}/ITO immunosensor revealed good linearity in the range of 1–70 ng dL{sup −1} with low detection limit of 8.715 ng/dL, improved sensitivity of 1.132 μA/(ng/dL cm{sup −2}), regression coefficient R{sup 2} of 0.918 and reproducibility of > 11 times. The association constant for the BSA/Ab-AFB1/nBi{sub 2}O{sub 3}/ITO immunosensor was determined as 7.318 ng/dL. - Highlights: • Use of Bismuth oxide nanorods for aflatoxin B1 detection. • It improved the electrochemical properties. • First report on nBi{sub 2}O{sub 3} for mycotoxin detection.

  4. Magnetic properties of the binary Nickel/Bismuth alloy

    Energy Technology Data Exchange (ETDEWEB)

    Keskin, Mustafa; Şarlı, Numan, E-mail: numansarli82@gmail.com

    2017-09-01

    Highlights: • We model and investigate the magnetic properties of the Ni/Bi alloy within the EFT. • Magnetizations of the Ni/Bi alloy are observed as Bi1 > Bi2 > Ni/Bi > Ni at T < Tc. • Magnetization of the Bi1 is dominant and Ni is at least dominant T < Tc. • Total magnetization of the Ni/Bi alloy is close to those of Ni at T < Tc. • Hysteresis curves are overlap at T < 0.1 and they behave separately at T > 0.1. - Abstract: Magnetic properties of the binary Nickel/Bismuth alloy (Ni/Bi) are investigated within the effective field theory. The Ni/Bi alloy has been modeled that the rhombohedral Bi lattice is surrounded by the hexagonal Ni lattice. According to lattice locations, Bi atoms have two different magnetic properties. Bi1 atoms are in the center of the hexagonal Ni atoms (Ni/Bi1 single layer) and Bi2 atoms are between two Ni/Bi1 bilayers. The Ni, Bi1, Bi2 and Ni/Bi undergo a second-order phase transition from the ferromagnetic phase to paramagnetic phase at Tc = 1.14. The magnetizations of the Ni/Bi alloy are observed as Bi1 > Bi2 > Ni/Bi > Ni at T < Tc; hence the magnetization of the Bi1 is dominant and Ni is at least dominant. However, the total magnetization of the Ni/Bi alloy is close to magnetization of the Ni at T < Tc. The corcivities of the Ni, Bi1, Bi2 and Ni/Bi alloy are the same with each others, but the remanence magnetizations are different. Our theoretical results of M(T) and M(H) of the Ni/Bi alloy are in quantitatively good agreement with the some experimental results of binary Nickel/Bismuth systems.

  5. Studies of corrosion resistance of Japanese steels in liquid lead-bismuth

    International Nuclear Information System (INIS)

    Kamata, Kin-ya; Ono, Hiroshi; Kitano, Teruaki; Ono, Mikinori

    2003-01-01

    Liquid lead-bismuth has attractive characteristics as a coolant in future fast reactors and Accelerator Driven Sub-critical Systems (ADS) applications. The corrosion behavior of structural materials in lead-bismuth eutectic is one of key problems in developing nuclear power plants and installations using lead-bismuth coolant. Our experiences with heat exchangers using liquid lead-bismuth and the results of corrosion tests of Japanese steels are reported in this paper. A series of corrosion tests was carried out in collaboration with the Institute of Physics and Power Engineering (IPPE). Test specimens of various Japanese steels were exposed in a non-isothermal forced circulation loop. The influence of maximum temperature and oxygen content in lead bismuth were chosen for study as the primary causes of corrosion in Japanese steels. After the corrosion tests, corrosion behavior was analyzed by visual inspection, measurement of weight loss and metallurgical examination of the microstructure of the corroded zone. The corrosion mechanism in liquid lead bismuth is discussed on the basis of the metallurgical examination of the corroded zone. (author)

  6. Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jagdale, Pravin, E-mail: pravin.jagdale@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy); Castellino, Micaela [Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Marrec, Françoise [Laboratory of Condensed Matter Physics, University of Picardie Jules Verne (UPJV), Amiens 80039 (France); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexicom (UNAM), Mexico D.F. 04510 (Mexico); Tagliaferro, Alberto [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy)

    2014-06-01

    Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl{sub 3}) in acetone (CH{sub 3}-CO-CH{sub 3}). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18–250 nm thick and a few micrometres wide.

  7. Evaluation of the strength and radiopacity of Portland cement with varying additions of bismuth oxide.

    Science.gov (United States)

    Saliba, E; Abbassi-Ghadi, S; Vowles, R; Camilleri, J; Hooper, S; Camilleri, J

    2009-04-01

    To study the effect of addition of various proportions of bismuth oxide on compressive strength and radiopacity of Portland cement. The compressive strength of white Portland cement and cement replaced with 10, 15, 20, 25 and 30% bismuth oxide was evaluated by testing cylinders 6 mm in diameter and 12 mm high. Twelve cylinders were tested for each material under study. The radiopacity of the cements tested was evaluated using an aluminium step-wedge and densitometer. The optical density was compared with the relevant thickness of aluminium (Al). Statistical analysis was performed using Analysis of Variance (ANOVA) with P = 0.05 and Tukey test to perform multiple comparison tests. Various additions of bismuth oxide had no significant effect on the strength of the material when compared with the unmodified Portland cement (P > 0.05). The radiopacity of the cements tested ranged from 2.02 mm Al for Portland cement to 9.79 mm Al for the highest bismuth replacement. Addition of bismuth oxide did not affect the compressive strength of Portland cement. All the bismuth oxide cement mixtures had radio-opacities higher than 3 mm thickness of aluminium.

  8. Extreme Pressure Synergistic Mechanism of Bismuth Naphthenate and Sulfurized Isobutene Additives

    Science.gov (United States)

    Xu, Xin; Hu, Jianqiang; Yang, Shizhao; Xie, Feng; Guo, Li

    A four-ball tester was used to evaluate the tribological performances of bismuth naphthenate (BiNap), sulfurized isobutene (VSB), and their combinations. The results show that the antiwear properties of BiNap and VSB are not very visible, but they possess good extreme pressure (EP) properties, particularly sulfur containing bismuth additives. Synergistic EP properties of BiNap with various sulfur-containing additives were investigated. The results indicate that BiNap exhibits good EP synergism with sulfur-containing additives. The surface analytical tools, such as X-ray photoelectron spectrometer (XPS) scanning electron microscope (SEM) and energy dispersive X-ray (EDX), were used to investigate the topography, composition contents, and depth profile of some typical elements on the rubbing surface. Smooth topography of wear scar further confirms that the additive showed good EP capacities, and XPS and EDX analyzes indicate that tribochemical mixed protective films composed of bismuth, bismuth oxides, sulfides, and sulfates are formed on the rubbing surface, which improves the tribological properties of lubricants. In particular, a large number of bismuth atoms and bismuth sulfides play an important role in improving the EP properties of oils.

  9. Intrinsic stress of bismuth oxide thin films: effect of vapour chopping and air ageing

    International Nuclear Information System (INIS)

    Patil, R B; Puri, R K; Puri, V

    2008-01-01

    Bismuth oxide thin films of thickness 1000 A 0 have been prepared by thermal oxidation (in air) of vacuum evaporated bismuth thin films (on glass substrate) at different oxidation temperatures and duration. Both the vapour chopped and nonchopped bismuth oxide thin films showed polycrystalline and polymorphic structure. The monoclinic bismuth oxide was found to be predominant in both the cases. The effect of vapour chopping and air exposure for 40 days on the intrinsic stress of bismuth oxide thin films has been studied. The vapour chopped films showed low (3.92 - 4.80 x 10 9 N/m 2 ) intrinsic stress than those of nonchopped bismuth oxide thin films (5.77 - 6.74 x 10 9 N/m 2 ). Intrinsic stress was found to increase due to air ageing. The effect of air ageing on the vapour chopped films was found low. The vapour chopped films showed higher packing density. Higher the packing density, lower the film will age. The process of chopping vapour flow creates films with less inhomogenety i.e. a low concentration of flaws and non-planar defects which results in lower intrinsic stress

  10. Photoluminescence of sol–gel synthesized PZT powders

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Aranda, M.C. [Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología-Universidad Autónoma de San Luis Potosí, Av. Sierra Leona No.550,Col. Lomas 2a. sección, C.P. 78210 San Luis Potosí, SLP, México (Mexico); Calderón-Piñar, F. [Centro de Investigación y de Estudios Avanzados del I.P.N. Unidad Querétaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, C.P. 7623 Querétaro, Qro, México (Mexico); Facultad de Física/IMRE, San Lázaro y L, Universidad de la Habana, C.P. 10400 Habana (Cuba); Hernández-Landaverde, M.A. [Centro de Investigación y de Estudios Avanzados del I.P.N. Unidad Querétaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, C.P. 7623 Querétaro, Qro, México (Mexico); and others

    2016-11-15

    A wide band of photoluminescence (PL) emission in structurally disordered lead zirconate titanate (PZT) powders, prepared by sol–gel route, was observed at room temperature excited with a laser line (488 nm). Powders with PbZr{sub 0.53}Ti{sub 0.47}O{sub 3} nominal composition annealed at different temperatures were studied by X-ray diffraction, Raman spectroscopy, Luminescence, Diffuse Reflectance and Electronic Paramagnetic Resonance Spectroscopy (EPR). Our results indicate that the PL response can be associated to order–disorder degree in the perovskite structure, with the exception of samples annealed at low temperature, where a mixture of oxides precursorsГ—Ві phases was observed. Furthermore, in quasi-crystalline ordered samples (95% of crystallinity) a small generation of PL remains. In these experiments, the band gap increases with the formation of crystalline structure. EPR experiments were conducted in order to follow the evolution of paramagnetic species with thermal treatment from the mixture of oxides precursors to the perovskite phase and paramagnetic point defects were identified (Pb{sup +3} and Ti{sup +3}). EPR data suggest the presence of order–disorder within the lattice network. Paramagnetic species are similar in samples treated at 700 and 800 °C, nevertheless the emission intensity decreases by a factor of 6, indicating that the defects associated with PL are not paramagnetic at both temperatures.

  11. HST observations of the limb polarization of Titan

    Science.gov (United States)

    Bazzon, A.; Schmid, H. M.; Buenzli, E.

    2014-12-01

    Context. Titan is an excellent test case for detailed studies of the scattering polarization from thick hazy atmospheres. Accurate scattering and polarization parameters have been provided by the in situ measurements of the Cassini-Huygens landing probe. For Earth-bound observations Titan can only be observed at a backscattering situation, where the disk-integrated polarization is close to zero. However, with resolved imaging polarimetry a second order polarization signal along the entire limb of Titan can be measured. Aims: We present the first limb polarization measurements of Titan, which are compared as a test to our limb polarization models. Methods: Previously unpublished imaging polarimetry from the HST archive is presented, which resolves the disk of Titan. We determine flux-weighted averages of the limb polarization and radial limb polarization profiles, and investigate the degradation and cancelation effects in the polarization signal due to the limited spatial resolution of our observations. Taking this into account we derive corrected values for the limb polarization in Titan. The results are compared with limb polarization models, using atmosphere and haze scattering parameters from the literature. Results: In the wavelength bands between 250 nm and 2 μm a strong limb polarization of about 2 - 7% is detected with a position angle perpendicular to the limb. The fractional polarization is highest around 1 μm. As a first approximation, the polarization seems to be equally strong along the entire limb. The comparison of our data with model calculations and the literature shows that the detected polarization is compatible with expectations from previous polarimetric observations taken with Voyager 2, Pioneer 11, and the Huygens probe. Conclusions: Our results indicate that ground-based monitoring measurements of the limb-polarization of Titan could be useful for investigating local haze properties and the impact of short-term and seasonal variations of

  12. Titan's Stratospheric Condensibles at High Northern Latitudes During Northern Winter

    Science.gov (United States)

    Anderson, Carrie; Samuelson, R.; Achterberg, R.

    2012-01-01

    The Infrared Interferometer Spectrometer (IRIS) instrument on board Voyager 1 caught the first glimpse of an unidentified particulate feature in Titan's stratosphere that spectrally peaks at 221 per centimeter. Until recently, this feature that we have termed 'the haystack,' has been seen persistently at high northern latitudes with the Composite Infrared Spectrometer (CIRS) instrument onboard Cassini, The strength of the haystack emission feature diminishes rapidly with season, becoming drastically reduced at high northern latitudes, as Titan transitions from northern winter into spring, In contrast to IRIS whose shortest wavenumber was 200 per centimeter, CIRS extends down to 10 per centimeter, thus revealing an entirely unexplored spectral region in which nitrile ices have numerous broad lattice vibration features, Unlike the haystack, which is only found at high northern latitudes during northern winter/early northern spring, this geometrically thin nitrile cloud pervades Titan's lower stratosphere, spectrally peaking at 160 per centimeter, and is almost global in extent spanning latitudes 85 N to 600 S, The inference of nitrile ices are consistent with the highly restricted altitude ranges over which these features are observed, and appear to be dominated by a mixture of HCN and HC3N, The narrow range in altitude over which the nitrile ices extend is unlike the haystack, whose vertical distribution is significantly broader, spanning roughly 70 kilometers in altitude in Titan's lower stratosphere, The nitrile clouds that CIRS observes are located in a dynamically stable region of Titan's atmosphere, whereas CH4 clouds, which ordinarily form in the troposphere, form in a more dynamically unstable region, where convective cloud systems tend to occur. In the unusual situation where Titan's tropopause cools significantly from the HASI 70.5K temperature minimum, CH4 should condense in Titan's lower stratosphere, just like the aforementioned nitrile clouds, although

  13. Extraction of lanthanide elements and bismuth in molten lithium chloride-liquid bismuth-lithium alloy system

    International Nuclear Information System (INIS)

    Harada, Makoto; Adachi, Motonari; Kai, Yuichi; Koike, Kenichi

    1987-01-01

    The equilibrium distributions of neodymium and samarium between molten LiCl and liquid Bi-Li alloy were measured in a wide range of Li-mole fraction in the alloy phase, X Li . These lanthanide elements were extracted through redox reactions. In high X Li range, X Li > 0.03, the distributions of neodymium and bismuth in the salt phase increased markedly. The anomalous increase is attributed to the formation of the compound comprized of Nd, Li, Bi and oxygen in the salt phase. The reaction processes in samarium and neodymium were very fast and the extraction rates are controlled by the diffusion processes of the solutes and metallic lithium. (author)

  14. Facile synthesis of bismuth oxyhalide nanosheet films with distinct conduction type and photo-induced charge carrier behavior

    Science.gov (United States)

    Jia, Huimin; He, Weiwei; Zhang, Beibei; Yao, Lei; Yang, Xiaokai; Zheng, Zhi

    2018-05-01

    A modified successive ionic layer adsorption and reaction (SILAR) method was developed to fabricate 2D ordered BiOX (X = CI, Br, I) nanosheet array films on FTO substrates at room temperature. The formation of BiOX films were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-vis absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). The semiconductor surface states determine the type of semiconductor. Although BiOCI, BiOBr and BiOI belong to the bismuth oxyhalide semiconductor family and possess similar crystal and electronic structures, they show different conductivity types due to their respective surface states. Mott-Schottky curve results demonstrate that the BiOCl and BiOI nanosheet arrays display n-type semiconductor properties, while the BiOBr films exhibit p-type semiconductor properties. Assisted by surface photovoltage (SPV) and transient photovoltage (TPV) techniques, the photoinduced charge transfer dynamics on the surface/interface of the BiOX/FTO nanosheet films were systematically and comparatively investigated. As revealed by the results, both the separation and transfer dynamics of the photo-induced carrier are influenced by film thickness.

  15. Manganese dioxide-supported silver bismuthate as an efficient electrocatalyst for oxygen reduction reaction in zinc-oxygen batteries

    International Nuclear Information System (INIS)

    Sun, Yanzhi; Yang, Meng; Pan, Junqing; Wang, Pingyuan; Li, Wei; Wan, Pingyu

    2016-01-01

    In this paper, we present a new efficient composite electrocatalyst, manganese dioxide-supported silver bismuthate (Ag 4 Bi 2 O 5 /MnO 2 ), for oxygen reduction reaction (ORR) in alkaline media. The new electrocatalyst was characterized with scanning electron microscope (SEM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements indicate that the Ag 4 Bi 2 O 5 /MnO 2 composite is a very efficient electrocatalyst for ORR in alkaline media. The physical and electrochemical characterization results suggest that the high activity is ascribed to the support effects from MnO 2 and the synergetic effects among Ag 4 Bi 2 O 5 and MnO 2 . The analysis of rotating disk electrode (RDE) results shows that the ORR occurs via a four-electron pathway on the surface of the Ag 4 Bi 2 O 5 /MnO 2 electrocatalyst. This electrocatalyst was further tested in a designed zinc–oxygen (Zn–O 2 ) battery. This battery can offer a discharge time of 225 h at 120 mA cm −2 , increasing by more than 492% as compared with pure MnO 2 electrocatalyst. It demonstrates that this inexpensive Ag 4 Bi 2 O 5 /MnO 2 electrocatalyst is a viable alternative to platinum electrocatalyst for energy conversion devices.

  16. Synthesis, crystal structure, and properties of a perovskite-related bismuth phase, (NH43Bi2I9

    Directory of Open Access Journals (Sweden)

    Shijing Sun

    2016-03-01

    Full Text Available Organic-inorganic halide perovskites, especially methylammonium lead halide, have recently led to remarkable advances in photovoltaic devices. However, due to environmental and stability concerns around the use of lead, research into lead-free perovskite structures has been attracting increasing attention. In this study, a layered perovskite-like architecture, (NH43Bi2I9, is prepared from solution and the structure solved by single crystal X-ray diffraction. The band gap, which is estimated to be 2.04 eV using UV-visible spectroscopy, is lower than that of CH3NH3PbBr3. The energy-minimized structure obtained from first principles calculations is in excellent agreement with the X-ray results and establishes the locations of the hydrogen atoms. The calculations also point to a significant lone pair effect on the bismuth ion. Single crystal and powder conductivity measurements are performed to examine the potential application of (NH43Bi2I9 as an alternative to the lead containing perovskites.

  17. Preliminary investigations of the copper/bismuth/tin system in a proposed new net-shaping process

    International Nuclear Information System (INIS)

    Macnamara, D.S.; Meltcalfe, R.D.; Krezalek, I.

    2002-01-01

    Full text: Mixed-phase near net-shape forming processes such as semi-solid and thixotropic moulding are receiving increasing interest. Problems met in these processes include homogenisation of the semi-solid melt and temperature control in the semi-solid region. Injection moulding of a paste of solid particles of relatively high melting point in a liquid metal matrix removes the need for precision temperature control. Ideally the process should also require neither mechanical stirring nor agitation. In this project, powder precursors are subjected to uniaxial compaction to improve particle distribution and provide good metal-to-metal contact. Static heating tests to determine the composition of the mixed-phase melt and dynamic tests to investigate the homogeneity, density and net shape of extruded samples have been carried out. Initial investigations have concentrated on copper particles suspended in a near-eutectic bismuth-tin alloy. This provides a good density match between liquid and solid phases, a low temperature melt, and good optical contrast for traditional metallography. We used the scanning electron microscope to highlight fine detail of microstructural features, and electron probe microanalysis for compositional information on the resultant material. Detailed results are presented. Copyright (2002) Australian Society for Electron Microscopy Inc

  18. Synthesis, characterization and enhanced thermoelectric performance of structurally ordered cable-like novel polyaniline–bismuth telluride nanocomposite

    International Nuclear Information System (INIS)

    Chatterjee, Krishanu; Mitra, Mousumi; Banerjee, Dipali; Kargupta, Kajari; Ganguly, Saibal

    2013-01-01

    Bismuth telluride (Bi 2 Te 3 ) nanorods and polyaniline (PANI) nanoparticles have been synthesized by employing solvothermal and chemical oxidative processes, respectively. Nanocomposites, comprising structurally ordered PANI preferentially grown along the surface of a Bi 2 Te 3 nanorods template, are synthesized using in situ polymerization. X-ray powder diffraction, UV–vis and Raman spectral analysis confirm the highly ordered chain structure of PANI on Bi 2 Te 3 nanorods, leading to a higher extent of doping, higher chain mobility and enhancement of the thermoelectric performance. Above 380 K, the PANI–Bi 2 Te 3 nanocomposite with a core–shell/cable-like structure exhibits a higher thermoelectric power factor than either pure PANI or Bi 2 Te 3 . At room temperature the thermal conductivity of the composite is lower than that of its pure constituents, due to selective phonon scattering by the nanointerfaces designed in the PANI–Bi 2 Te 3 nanocable structures. The figure of merit of the nanocomposite at room temperature is comparable to the values reported in the literature for bulk polymer-based composite thermoelectric materials. (paper)

  19. Titan Orbiter Aerorover Mission with Enceladus Science (TOAMES)

    Science.gov (United States)

    Sittler, E.; Cooper, J.; Mahaffy, P.; Fairbrother, D.; de Pater, I.; Schulze-Makuch, D.; Pitman, J.

    2007-08-01

    same time made us aware of how little we understand about these bodies. For example, the source, and/or recycling mechanism, of methane in Titan's atmosphere is still puzzling. Indeed, river beds (mostly dry) and lakes have been spotted, and occasional clouds have been seen, but the physics to explain the observations is still mostly lacking, since our "image" of Titan is still sketchy and quite incomplete. Enceladus, only 500 km in extent, is even more puzzling, with its fiery plumes of vapor, dust and ice emanating from its south polar region, "feeding" Saturn's E ring. Long term variability of magnetospheric plasma, neutral gas, E-ring ice grain density, radio emissions, and corotation of Saturn's planetary magnetic field in response to Enceladus plume activity are of great interest for Saturn system science. Both Titan and Enceladus are bodies of considerable astrobiological interest in view of high organic abundances at Titan and potential subsurface liquid water at Enceladus. We propose to develop a new mission to Titan and Enceladus, the Titan Orbiter Aerorover Mission with Enceladus Science (TOAMES), to address these questions using novel new technologies. TOAMES is a multi-faceted mission that starts with orbit insertion around Saturn using aerobraking with Titan's extended atmosphere. We then have an orbital tour around Saturn (for 1-2 years) and close encounters with Enceladus, before it goes into orbit around Titan (via aerocapture). During the early reconnaissance phase around Titan, perhaps 6 months long, the orbiter will use altimetry, radio science and remote sensing instruments to measure Titan's global topography, subsurface structure and atmospheric winds. This information will be used to determine where and when to release the Aerorover, so that it can navigate safely around Titan and identify prime sites for surface sampling and analysis. In situ instruments will sample the upper atmosphere which may provide the seed population for the complex

  20. Development of titanium based biocomposite by powder metallurgy processing with in situ forming of Ca-P phases

    Energy Technology Data Exchange (ETDEWEB)

    Karanjai, Malobika [International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur P.O., Hyderabad 500005, Andhra Pradesh (India)]. E-mail: malobika@arci.res.in; Sundaresan, Ranganathan [International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur P.O., Hyderabad 500005, Andhra Pradesh (India); Rao, Gummididala Venkata Narasimha [International Advanced Research Centre for Powder Metallurgy and New Materials, Balapur P.O., Hyderabad 500005, Andhra Pradesh (India); Mohan, Tallapragada Raja Rama [Metallurgical Engineering and Materials Science Department, Indian Institute of Technology, Powai, Mumbai 400076, Maharashtra (India); Kashyap, Bhagwati Prasad [Metallurgical Engineering and Materials Science Department, Indian Institute of Technology, Powai, Mumbai 400076, Maharashtra (India)

    2007-02-25

    Composites of titanium and calcium-phosphorus phases were developed by powder metallurgy processing and evaluated for bioactivity. Titanium hydride powder and precursors of calcium and phosphorus in the form of calcium carbonate and di-ammonium hydrogen orthophosphate were mixed in different proportions, compacted and calcined in different atmospheres. The calcined compacts were subsequently crushed, recompacted and sintered in vacuum. In situ formation of bioactive phases like hydroxylapatite, tricalcium phosphate and calcium titanate during the calcination and sintering steps was studied using X-ray diffraction. The effect of calcination atmosphere on density, interconnected porosity, phase composition and modulus of rupture of sintered composites was examined. The sintered composites were immersed in simulated body fluid for 7 days to observe their in vitro behaviour with XRD and FTIR spectroscopic identification of deposits. Composites with 10 wt% precursors sintered from vacuum calcined powder gave the best results in terms of bioactive phases, density and strength.